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2023-01-20serial: exar: Add support for Sealevel 7xxxC serial cardsMatthew Howell1-0/+14
Add support for Sealevel 7xxxC serial cards. This patch: * Adds IDs to recognize 7xxxC cards from Sealevel Systems. * Updates exar_pci_probe() to set nr_ports to last two bytes of primary dev ID for these cards. Signed-off-by: Matthew Howell <matthew.howell@sealevel.com> Cc: stable <stable@kernel.org> Link: https://lore.kernel.org/r/alpine.DEB.2.21.2301191440010.22558@tstest-VirtualBox Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-12-16Merge tag 'tty-6.2-rc1' of ↵Linus Torvalds6-17/+141
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty Pull tty/serial driver updates from Greg KH: "Here is the "big" set of tty/serial driver changes for 6.2-rc1. As in previous kernel releases, nothing big here at all, just some small incremental serial/tty layer cleanups and some individual driver additions and fixes. Highlights are: - serial helper macros from Jiri Slaby to reduce the amount of duplicated code in serial drivers - api cleanups and consolidations from Ilpo Järvinen in lots of serial drivers - the usual set of n_gsm fixes from Daniel Starke as that code gets exercised more - TIOCSTI is finally able to be disabled if requested (security hardening feature from Kees Cook) - fsl_lpuart driver fixes and features added - other small serial driver additions and fixes All of these have been in linux-next for a while with no reported problems" * tag 'tty-6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (97 commits) serial: atmel: don't stop the transmitter when doing PIO serial: atmel: cleanup atmel_start+stop_tx() tty: serial: fsl_lpuart: switch to new dmaengine_terminate_* API serial: sunsab: Fix error handling in sunsab_init() serial: altera_uart: fix locking in polling mode serial: pch: Fix PCI device refcount leak in pch_request_dma() tty: serial: fsl_lpuart: Use pm_ptr() to avoid need to make pm __maybe_unused tty: serial: fsl_lpuart: Add runtime pm support tty: serial: fsl_lpuart: enable wakeup source for lpuart serdev: Replace poll loop by readx_poll_timeout() macro tty: synclink_gt: unwind actions in error path of net device open serial: stm32: move dma_request_chan() before clk_prepare_enable() dt-bindings: serial: xlnx,opb-uartlite: Drop 'contains' from 'xlnx,use-parity' serial: pl011: Do not clear RX FIFO & RX interrupt in unthrottle. serial: amba-pl011: avoid SBSA UART accessing DMACR register tty: serial: altera_jtaguart: remove struct altera_jtaguart tty: serial: altera_jtaguart: use uart_port::read_status_mask tty: serial: altera_jtaguart: remove unused altera_jtaguart::sigs tty: serial: altera_jtaguart: remove flag from altera_jtaguart_rx_chars() n_tty: Rename tail to old_tail in n_tty_read() ...
2022-12-12Merge tag 'printk-for-6.2' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux Pull printk updates from Petr Mladek: - Add NMI-safe SRCU reader API. It uses atomic_inc() instead of this_cpu_inc() on strong load-store architectures. - Introduce new console_list_lock to synchronize a manipulation of the list of registered consoles and their flags. This is a first step in removing the big-kernel-lock-like behavior of console_lock(). This semaphore still serializes console->write() calbacks against: - each other. It primary prevents potential races between early and proper console drivers using the same device. - suspend()/resume() callbacks and init() operations in some drivers. - various other operations in the tty/vt and framebufer susbsystems. It is likely that console_lock() serializes even operations that are not directly conflicting with the console->write() callbacks here. This is the most complicated big-kernel-lock aspect of the console_lock() that will be hard to untangle. - Introduce new console_srcu lock that is used to safely iterate and access the registered console drivers under SRCU read lock. This is a prerequisite for introducing atomic console drivers and console kthreads. It will reduce the complexity of serialization against normal consoles and console_lock(). Also it should remove the risk of deadlock during critical situations, like Oops or panic, when only atomic consoles are registered. - Check whether the console is registered instead of enabled on many locations. It was a historical leftover. - Cleanly force a preferred console in xenfb code instead of a dirty hack. - A lot of code and comment clean ups and improvements. * tag 'printk-for-6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: (47 commits) printk: htmldocs: add missing description tty: serial: sh-sci: use setup() callback for early console printk: relieve console_lock of list synchronization duties tty: serial: kgdboc: use console_list_lock to trap exit tty: serial: kgdboc: synchronize tty_find_polling_driver() and register_console() tty: serial: kgdboc: use console_list_lock for list traversal tty: serial: kgdboc: use srcu console list iterator proc: consoles: use console_list_lock for list iteration tty: tty_io: use console_list_lock for list synchronization printk, xen: fbfront: create/use safe function for forcing preferred netconsole: avoid CON_ENABLED misuse to track registration usb: early: xhci-dbc: use console_is_registered() tty: serial: xilinx_uartps: use console_is_registered() tty: serial: samsung_tty: use console_is_registered() tty: serial: pic32_uart: use console_is_registered() tty: serial: earlycon: use console_is_registered() tty: hvc: use console_is_registered() efi: earlycon: use console_is_registered() tty: nfcon: use console_is_registered() serial_core: replace uart_console_enabled() with uart_console_registered() ...
2022-12-02serial_core: replace uart_console_enabled() with uart_console_registered()John Ogness1-1/+1
All users of uart_console_enabled() really want to know if a console is registered. It is not reliable to check for CON_ENABLED in order to identify if a console is registered. Use console_is_registered() instead. A _locked() variant is provided because uart_set_options() is always called with the console_list_lock held and must check if a console is registered in order to synchronize with kgdboc. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20221116162152.193147-23-john.ogness@linutronix.de
2022-11-22Merge 6.1-rc6 into tty-nextGreg Kroah-Hartman6-31/+51
We need the tty/serial fixes in here as well. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-11-18Merge tag 'tty-6.1-rc6' of ↵Linus Torvalds3-28/+48
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty Pull tty/serial driver fixes from Greg KH: "Here are a number of small tty and serial driver fixes for 6.1-rc6. They all resolve reported problems: - kernel doc build problems with the -rc1 serial driver documentation update - n_gsm reported problems - imx serial driver missing callback - lots of tiny 8250 driver fixes for reported issues. All of these have been in linux-next for over a week with no reported problems" * tag 'tty-6.1-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: docs/driver-api/miscellaneous: Remove kernel-doc of serial_core.c serial: 8250: Flush DMA Rx on RLSI serial: 8250_lpss: Use 16B DMA burst with Elkhart Lake serial: 8250_lpss: Configure DMA also w/o DMA filter serial: 8250: Fall back to non-DMA Rx if IIR_RDI occurs tty: n_gsm: fix sleep-in-atomic-context bug in gsm_control_send Revert "tty: n_gsm: replace kicktimer with delayed_work" Revert "tty: n_gsm: avoid call of sleeping functions from atomic context" serial: imx: Add missing .thaw_noirq hook tty: serial: fsl_lpuart: don't break the on-going transfer when global reset serial: 8250: omap: Flush PM QOS work on remove serial: 8250: omap: Fix unpaired pm_runtime_put_sync() in omap8250_remove() serial: 8250_omap: remove wait loop from Errata i202 workaround serial: 8250: omap: Fix missing PM runtime calls for omap8250_set_mctrl() serial: 8250: 8250_omap: Avoid RS485 RTS glitch on ->set_termios()
2022-11-09serial: 8250: Flush DMA Rx on RLSIIlpo Järvinen1-2/+1
Returning true from handle_rx_dma() without flushing DMA first creates a data ordering hazard. If DMA Rx has handled any character at the point when RLSI occurs, the non-DMA path handles any pending characters jumping them ahead of those characters that are pending under DMA. Fixes: 75df022b5f89 ("serial: 8250_dma: Fix RX handling") Cc: <stable@vger.kernel.org> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20221108121952.5497-5-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-11-09serial: 8250_lpss: Use 16B DMA burst with Elkhart LakeIlpo Järvinen1-0/+2
Configure DMA to use 16B burst size with Elkhart Lake. This makes the bus use more efficient and works around an issue which occurs with the previously used 1B. The fix was initially developed by Srikanth Thokala and Aman Kumar. This together with the previous config change is the cleaned up version of the original fix. Fixes: 0a9410b981e9 ("serial: 8250_lpss: Enable DMA on Intel Elkhart Lake") Cc: <stable@vger.kernel.org> # serial: 8250_lpss: Configure DMA also w/o DMA filter Reported-by: Wentong Wu <wentong.wu@intel.com> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20221108121952.5497-4-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-11-09serial: 8250_lpss: Configure DMA also w/o DMA filterIlpo Järvinen1-4/+11
If the platform doesn't use DMA device filter (as is the case with Elkhart Lake), whole lpss8250_dma_setup() setup is skipped. This results in skipping also *_maxburst setup which is undesirable. Refactor lpss8250_dma_setup() to configure DMA even if filter is not setup. Cc: stable <stable@kernel.org> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20221108121952.5497-3-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-11-09serial: 8250: Fall back to non-DMA Rx if IIR_RDI occursIlpo Järvinen1-0/+4
DW UART sometimes triggers IIR_RDI during DMA Rx when IIR_RX_TIMEOUT should have been triggered instead. Since IIR_RDI has higher priority than IIR_RX_TIMEOUT, this causes the Rx to hang into interrupt loop. The problem seems to occur at least with some combinations of small-sized transfers (I've reproduced the problem on Elkhart Lake PSE UARTs). If there's already an on-going Rx DMA and IIR_RDI triggers, fall graciously back to non-DMA Rx. That is, behave as if IIR_RX_TIMEOUT had occurred. 8250_omap already considers IIR_RDI similar to this change so its nothing unheard of. Fixes: 75df022b5f89 ("serial: 8250_dma: Fix RX handling") Cc: <stable@vger.kernel.org> Co-developed-by: Srikanth Thokala <srikanth.thokala@intel.com> Signed-off-by: Srikanth Thokala <srikanth.thokala@intel.com> Co-developed-by: Aman Kumar <aman.kumar@intel.com> Signed-off-by: Aman Kumar <aman.kumar@intel.com> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20221108121952.5497-2-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-11-09serial: 8250: 8250_omap: Fix calculation of RS485 delaysLukas Wunner1-1/+1
Commit 801954d1210a ("serial: 8250: 8250_omap: Support native RS485") calculates RS485 delays from the baudrate. The baudrate is generated with either a 16x or 13x divisor. The divisor is set in the Mode Definition Register 1 (MDR1). The commit erroneously assumes that the register stores the divisor as a bitmask and uses a logical AND to differentiate between 16x and 13x divisors. However the divisor is really stored as a 3-bit mode (see lines 363ff in include/uapi/linux/serial_reg.h). The logical AND operation is performed with UART_OMAP_MDR1_16X_MODE, which is defined as 0x0 and hence yields false. So the commit always assumes a 13x divisor. Fix by using an equal comparison. This works because we never set any of the other 5 bits in the register. (They pertain to IrDA mode, which is not supported by the driver). Fixes: 801954d1210a ("serial: 8250: 8250_omap: Support native RS485") Link: https://lore.kernel.org/linux-serial/202211070440.8hWunFUN-lkp@intel.com/ Reported-by: kernel test robot <lkp@intel.com> Reported-by: Dan Carpenter <error27@gmail.com> Signed-off-by: Lukas Wunner <lukas@wunner.de> Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://lore.kernel.org/r/7d5b04da13d89b8708b9543a0b125f2b6062a77b.1667977259.git.lukas@wunner.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-11-09serial: 8250_bcm7271: Fix error handling in brcmuart_init()Yuan Can1-1/+9
A problem about 8250_bcm7271 create debugfs failed is triggered with the following log given: [ 324.516635] debugfs: Directory 'bcm7271-uart' with parent '/' already present! The reason is that brcmuart_init() returns platform_driver_register() directly without checking its return value, if platform_driver_register() failed, it returns without destroy the newly created debugfs, resulting the debugfs of 8250_bcm7271 can never be created later. brcmuart_init() debugfs_create_dir() # create debugfs directory platform_driver_register() driver_register() bus_add_driver() priv = kzalloc(...) # OOM happened # return without destroy debugfs directory Fix by removing debugfs when platform_driver_register() returns error. Fixes: 41a469482de2 ("serial: 8250: Add new 8250-core based Broadcom STB driver") Signed-off-by: Yuan Can <yuancan@huawei.com> Link: https://lore.kernel.org/r/20221109072110.117291-2-yuancan@huawei.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-11-09serial: 8250_dma: Rearm DMA Rx if more data is pendingIlpo Järvinen1-3/+16
When DMA Rx completes, the current behavior is to just exit the DMA completion handler without future actions. If the transfer is still on-going, UART will trigger an interrupt and that eventually rearms the DMA Rx. The extra interrupt round-trip has an inherent latency cost that increases the risk of FIFO overrun. In such situations, the latency margin tends to already be less due to FIFO not being empty. Add check into DMA Rx completion handler to detect if LSR has DR (Data Ready) still set. DR indicates there will be more characters pending and DMA Rx can be rearmed right away to handle them. Cc: Gilles BULOZ <gilles.buloz@kontron.com> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20221107102126.56481-1-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-11-03serial: 8250_core: Use str_enabled_disabled() helperAndy Shevchenko1-2/+3
Use str_enabled_disabled() helper instead of open coding the same. Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20221017171633.65275-1-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-11-03serial: 8250: omap: Flush PM QOS work on removeTony Lindgren1-0/+1
Rebinding 8250_omap in a loop will at some point produce a warning for kernel/power/qos.c:296 cpu_latency_qos_update_request() with error "cpu_latency_qos_update_request called for unknown object". Let's flush the possibly pending PM QOS work scheduled from omap8250_runtime_suspend() before we disable runtime PM. Fixes: 61929cf0169d ("tty: serial: Add 8250-core based omap driver") Signed-off-by: Tony Lindgren <tony@atomide.com> Link: https://lore.kernel.org/r/20221028110044.54719-1-tony@atomide.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-11-03serial: 8250: omap: Fix unpaired pm_runtime_put_sync() in omap8250_remove()Tony Lindgren1-0/+5
On remove, we get an error for "Runtime PM usage count underflow!". I guess this driver is mostly built-in, and this issue has gone unnoticed for a while. Somehow I did not catch this issue with my earlier fix done with commit 4e0f5cc65098 ("serial: 8250_omap: Fix probe and remove for PM runtime"). Fixes: 4e0f5cc65098 ("serial: 8250_omap: Fix probe and remove for PM runtime") Signed-off-by: Tony Lindgren <tony@atomide.com> Depends-on: dd8088d5a896 ("PM: runtime: Add pm_runtime_resume_and_get to deal with usage counter") Link: https://lore.kernel.org/r/20221028105813.54290-1-tony@atomide.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-11-03serial: 8250_omap: remove wait loop from Errata i202 workaroundMatthias Schiffer1-17/+0
We were occasionally seeing the "Errata i202: timedout" on an AM335x board when repeatedly opening and closing a UART connected to an active sender. As new input may arrive at any time, it is possible to miss the "RX FIFO empty" condition, forcing the loop to wait until it times out. Nothing in the i202 Advisory states that such a wait is even necessary; other FIFO clear functions like serial8250_clear_fifos() do not wait either. For this reason, it seems safe to remove the wait, fixing the mentioned issue. Fixes: 61929cf0169d ("tty: serial: Add 8250-core based omap driver") Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com> Link: https://lore.kernel.org/r/20221013112339.2540767-1-matthias.schiffer@ew.tq-group.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-11-03serial: 8250: omap: Fix missing PM runtime calls for omap8250_set_mctrl()Tony Lindgren1-2/+20
There are cases where omap8250_set_mctrl() may get called after the UART has already autoidled causing an asynchronous external abort. This can happen on ttyport_open(): mem_serial_in from omap8250_set_mctrl+0x38/0xa0 omap8250_set_mctrl from uart_update_mctrl+0x4c/0x58 uart_update_mctrl from uart_dtr_rts+0x60/0xa8 uart_dtr_rts from tty_port_block_til_ready+0xd0/0x2a8 tty_port_block_til_ready from uart_open+0x14/0x1c uart_open from ttyport_open+0x64/0x148 And on ttyport_close(): omap8250_set_mctrl from uart_update_mctrl+0x3c/0x48 uart_update_mctrl from uart_dtr_rts+0x54/0x9c uart_dtr_rts from tty_port_shutdown+0x78/0x9c tty_port_shutdown from tty_port_close+0x3c/0x74 tty_port_close from ttyport_close+0x40/0x58 It can also happen on disassociate_ctty() calling uart_shutdown() that ends up calling omap8250_set_mctrl(). Let's fix the issue by adding missing PM runtime calls to omap8250_set_mctrl(). To do this, we need to add __omap8250_set_mctrl() that can be called from both omap8250_set_mctrl(), and from runtime PM resume path when restoring the registers. Fixes: 61929cf0169d ("tty: serial: Add 8250-core based omap driver") Reported-by: Merlijn Wajer <merlijn@wizzup.org> Reported-by: Romain Naour <romain.naour@smile.fr> Reported-by: Ivaylo Dimitrov <ivo.g.dimitrov.75@gmail.com> Tested-by: Ivaylo Dimitrov <ivo.g.dimitrov.75@gmail.com> Signed-off-by: Tony Lindgren <tony@atomide.com> Depends-on: dd8088d5a896 ("PM: runtime: Add pm_runtime_resume_and_get to deal with usage counter") Link: https://lore.kernel.org/r/20221024063613.25943-1-tony@atomide.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-11-03serial: 8250: 8250_omap: Avoid RS485 RTS glitch on ->set_termios()Lukas Wunner1-3/+4
RS485-enabled UART ports on TI Sitara SoCs with active-low polarity exhibit a Transmit Enable glitch on ->set_termios(): omap8250_restore_regs(), which is called from omap_8250_set_termios(), sets the TCRTLR bit in the MCR register and clears all other bits, including RTS. If RTS uses active-low polarity, it is now asserted for no reason. The TCRTLR bit is subsequently cleared by writing up->mcr to the MCR register. That variable is always zero, so the RTS bit is still cleared (incorrectly so if RTS is active-high). (up->mcr is not, as one might think, a cache of the MCR register's current value. Rather, it only caches a single bit of that register, the AFE bit. And it only does so if the UART supports the AFE bit, which OMAP does not. For details see serial8250_do_set_termios() and serial8250_do_set_mctrl().) Finally at the end of omap8250_restore_regs(), the MCR register is restored (and RTS deasserted) by a call to up->port.ops->set_mctrl() (which equals serial8250_set_mctrl()) and serial8250_em485_stop_tx(). So there's an RTS glitch between setting TCRTLR and calling serial8250_em485_stop_tx(). Avoid by using a read-modify-write when setting TCRTLR. While at it, drop a redundant initialization of up->mcr. As explained above, the variable isn't used by the driver and it is already initialized to zero because it is part of the static struct serial8250_ports[] declared in 8250_core.c. (Static structs are initialized to zero per section 6.7.8 nr. 10 of the C99 standard.) Cc: Jan Kiszka <jan.kiszka@siemens.com> Cc: Su Bao Cheng <baocheng.su@siemens.com> Tested-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com> Signed-off-by: Lukas Wunner <lukas@wunner.de> Link: https://lore.kernel.org/r/6554b0241a2c7fd50f32576fdbafed96709e11e8.1664278942.git.lukas@wunner.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-11-03serial: 8250/ingenic: Add support for the JZ4750/JZ4755Siarhei Volkau1-3/+29
JZ4750/55/60 (but not JZ4760b) have an optional /2 divider between the EXT oscillator and some peripherals including UART, which will be enabled if using a 24 MHz oscillator, and disabled when using a 12 MHz oscillator. This behavior relies on hardware differences: most boards (if not all) with those SoCs have 12 or 24 MHz oscillators but many peripherals want 12Mhz to operate properly (AIC and USB-PHY at least). The 16MHz threshold looks arbitrary but used in vendor's bootloader code for enable the divider. The patch doesn't affect JZ4760's behavior as it is subject for another patchset with re-classification of all supported ingenic UARTs. Link: https://github.com/carlos-wong/uboot_jz4755/blob/master/cpu/mips/jz_serial.c#L158 Signed-off-by: Siarhei Volkau <lis8215@gmail.com> Link: https://lore.kernel.org/r/20221031184041.1338129-3-lis8215@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-11-03serial: 8250: Use uart_xmit_advance()Ilpo Järvinen1-2/+1
Take advantage of the new uart_xmit_advance() helper. Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://lore.kernel.org/r/20221019091151.6692-8-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-11-03serial: 8250_bcm7271: Use uart_xmit_advance()Ilpo Järvinen1-3/+1
Take advantage of the new uart_xmit_advance() helper. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://lore.kernel.org/r/20221019091151.6692-7-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-11-03serial: 8250: 8250_omap: Support native RS485Lukas Wunner1-3/+82
Recent TI Sitara SoCs such as AM64/AM65 have gained the ability to automatically assert RTS when data is transmitted, obviating the need to emulate this functionality in software. The feature is controlled through new DIR_EN and DIR_POL bits in the Mode Definition Register 3. For details see page 8783 and 8890 of the AM65 TRM: https://www.ti.com/lit/ug/spruid7e/spruid7e.pdf Cc: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Cc: Su Bao Cheng <baocheng.su@siemens.com> Cc: Vignesh Raghavendra <vigneshr@ti.com> Cc: Jan Kiszka <jan.kiszka@siemens.com> Cc: Bin Liu <b-liu@ti.com> Tested-by: Zeng Chao <chao.zeng@siemens.com> Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Signed-off-by: Lukas Wunner <lukas@wunner.de> Link: https://lore.kernel.org/r/e9f25f5c9200a35d3162973c2b45d6b892cc9bf2.1665906869.git.lukas@wunner.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-10-21parisc/serial: Rename 8250_gsc.c to 8250_parisc.cHelge Deller3-2/+2
The file name of this driver is misleading - it handles various serial ports on parisc machines, not just such on the GSC bus. Rename the file to make this clearer. Suggested-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Helge Deller <deller@gmx.de>
2022-10-21parisc: Make 8250_gsc driver dependend on CONFIG_PARISCHelge Deller1-1/+1
Although the name of the driver 8250_gsc.c suggests that it handles only serial ports on the GSC bus, it does handle serial ports listed in the parisc machine inventory as well, e.g. the serial ports in a C8000 PCI-only workstation. Change the dependency to CONFIG_PARISC, so that the driver gets included in the kernel even if CONFIG_GSC isn't set. Reported-by: Mikulas Patocka <mpatocka@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Helge Deller <deller@gmx.de>
2022-09-25serial: 8250: Fix restoring termios speed after suspendPali Rohár1-1/+6
Since commit edc6afc54968 ("tty: switch to ktermios and new framework") termios speed is no longer stored only in c_cflag member but also in new additional c_ispeed and c_ospeed members. If BOTHER flag is set in c_cflag then termios speed is stored only in these new members. Since commit 027b57170bf8 ("serial: core: Fix initializing and restoring termios speed") termios speed is available also in struct console. So properly restore also c_ispeed and c_ospeed members after suspend to fix restoring termios speed which is not represented by Bnnn constant. Fixes: 4516d50aabed ("serial: 8250: Use canary to restart console after suspend") Signed-off-by: Pali Rohár <pali@kernel.org> Link: https://lore.kernel.org/r/20220924104324.4035-1-pali@kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-09-25serial: Deassert Transmit Enable on probe in driver-specific wayLukas Wunner3-13/+11
When a UART port is newly registered, uart_configure_port() seeks to deassert RS485 Transmit Enable by setting the RTS bit in port->mctrl. However a number of UART drivers interpret a set RTS bit as *assertion* instead of deassertion: Affected drivers include those using serial8250_em485_config() (except 8250_bcm2835aux.c) and some using mctrl_gpio (e.g. imx.c). Since the interpretation of the RTS bit is driver-specific, it is not suitable as a means to centrally deassert Transmit Enable in the serial core. Instead, the serial core must call on drivers to deassert it in their driver-specific way. One way to achieve that is to call ->rs485_config(). It implicitly deasserts Transmit Enable. So amend uart_configure_port() and uart_resume_port() to invoke uart_rs485_config(). That allows removing calls to uart_rs485_config() from drivers' ->probe() hooks and declaring the function static. Skip any invocation of ->set_mctrl() if RS485 is enabled. RS485 has no hardware flow control, so the modem control lines are irrelevant and need not be touched. When leaving RS485 mode, reset the modem control lines to the state stored in port->mctrl. That way, UARTs which are muxed between RS485 and RS232 transceivers drive the lines correctly when switched to RS232. (serial8250_do_startup() historically raises the OUT1 modem signal because otherwise interrupts are not signaled on ancient PC UARTs, but I believe that no longer applies to modern, RS485-capable UARTs and is thus safe to be skipped.) imx.c modifies port->mctrl whenever Transmit Enable is asserted and deasserted. Stop it from doing that so port->mctrl reflects the RS232 line state. 8250_omap.c deasserts Transmit Enable on ->runtime_resume() by calling ->set_mctrl(). Because that is now a no-op in RS485 mode, amend the function to call serial8250_em485_stop_tx(). fsl_lpuart.c retrieves and applies the RS485 device tree properties after registering the UART port. Because applying now happens on registration in uart_configure_port(), move retrieval of the properties ahead of uart_add_one_port(). Link: https://lore.kernel.org/all/20220329085050.311408-1-matthias.schiffer@ew.tq-group.com/ Link: https://lore.kernel.org/all/8f538a8903795f22f9acc94a9a31b03c9c4ccacb.camel@ginzinger.com/ Fixes: d3b3404df318 ("serial: Fix incorrect rs485 polarity on uart open") Cc: stable@vger.kernel.org # v4.14+ Reported-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com> Reported-by: Roosen Henri <Henri.Roosen@ginzinger.com> Tested-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com> Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Signed-off-by: Lukas Wunner <lukas@wunner.de> Link: https://lore.kernel.org/r/2de36eba3fbe11278d5002e4e501afe0ceaca039.1663863805.git.lukas@wunner.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-09-25serial: 8250_dma: Convert to use uart_xmit_advance()Andy Shevchenko1-3/+1
uart_xmit_advance() provides a common way on how to advance the Tx queue. Use it for the sake of unification and robustness. Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20220909091102.58941-1-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-09-25serial: 8250_omap: Convert to use uart_xmit_advance()Andy Shevchenko1-3/+1
uart_xmit_advance() provides a common way on how to advance the Tx queue. Use it for the sake of unification and robustness. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20220909091258.68886-1-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-09-25Merge 7e2cd21e02b3 ("Merge tag 'tty-6.0-rc7' of ↵Greg Kroah-Hartman1-0/+1
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty") into tty-next We need the tty fixes and api additions in this branch. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-09-22serial: 8250: omap: Use serial8250_em485_supportedMatthias Schiffer1-0/+1
8250_omap uses em485, fill in rs485_supported accordingly. This makes RS485 work with 8250_omap again, which was broken with the introduction of the RS485 config sanitization. Fixes: be2e2cb1d2819 ("serial: Sanitize rs485_struct") Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com> Link: https://lore.kernel.org/r/20220916110955.161099-1-matthias.schiffer@ew.tq-group.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-09-22serial: 8250: Toggle IER bits on only after irq has been set upIlpo Järvinen2-8/+16
Invoking TIOCVHANGUP on 8250_mid port on Ice Lake-D and then reopening the port triggers these faults during serial8250_do_startup(): DMAR: DRHD: handling fault status reg 3 DMAR: [DMA Write NO_PASID] Request device [00:1a.0] fault addr 0x0 [fault reason 0x05] PTE Write access is not set If the IRQ hasn't been set up yet, the UART will have zeroes in its MSI address/data registers. Disabling the IRQ at the interrupt controller won't stop the UART from performing a DMA write to the address programmed in its MSI address register (zero) when it wants to signal an interrupt. The UARTs (in Ice Lake-D) implement PCI 2.1 style MSI without masking capability, so there is no way to mask the interrupt at the source PCI function level, except disabling the MSI capability entirely, but that would cause it to fall back to INTx# assertion, and the PCI specification prohibits disabling the MSI capability as a way to mask a function's interrupt service request. The MSI address register is zeroed by the hangup as the irq is freed. The interrupt is signalled during serial8250_do_startup() performing a THRE test that temporarily toggles THRI in IER. The THRE test currently occurs before UART's irq (and MSI address) is properly set up. Refactor serial8250_do_startup() such that irq is set up before the THRE test. The current irq setup code is intermixed with the timer setup code. As THRE test must be performed prior to the timer setup, extract it into own function and call it only after the THRE test. The ->setup_timer() needs to be part of the struct uart_8250_ops in order to not create circular dependency between 8250 and 8250_base modules. Fixes: 40b36daad0ac ("[PATCH] 8250 UART backup timer") Reported-by: Lennert Buytenhek <buytenh@arista.com> Tested-by: Lennert Buytenhek <buytenh@arista.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://lore.kernel.org/r/20220922070005.2965-1-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-09-22serial: 8250: Request full 16550A feature probing for OxSemi PCIe devicesMaciej W. Rozycki1-0/+5
Oxford Semiconductor PCIe (Tornado) 950 serial port devices need to operate in the enhanced mode via the EFR register for the Divide-by-M N/8 baud rate generator prescaler to be used in their native UART mode. Otherwise the prescaler is fixed at 1 causing grossly incorrect baud rates to be programmed. Accessing the EFR register requires 16550A features to have been probed for, so request this to happen regardless of SERIAL_8250_16550A_VARIANTS by setting UPF_FULL_PROBE in port flags. Fixes: 366f6c955d4d ("serial: 8250: Add proper clock handling for OxSemi PCIe devices") Cc: stable@vger.kernel.org # v5.19+ Reported-by: Anders Blomdell <anders.blomdell@control.lth.se> Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk> Link: https://lore.kernel.org/r/alpine.DEB.2.21.2209210005040.41633@angie.orcam.me.uk Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-09-22serial: 8250: Let drivers request full 16550A feature probingMaciej W. Rozycki1-1/+2
A SERIAL_8250_16550A_VARIANTS configuration option has been recently defined that lets one request the 8250 driver not to probe for 16550A device features so as to reduce the driver's device startup time in virtual machines. Some actual hardware devices require these features to have been fully determined however for their driver to work correctly, so define a flag to let drivers request full 16550A feature probing on a device-by-device basis if required regardless of the SERIAL_8250_16550A_VARIANTS option setting chosen. Fixes: dc56ecb81a0a ("serial: 8250: Support disabling mdelay-filled probes of 16550A variants") Cc: stable@vger.kernel.org # v5.6+ Reported-by: Anders Blomdell <anders.blomdell@control.lth.se> Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk> Link: https://lore.kernel.org/r/alpine.DEB.2.21.2209202357520.41633@angie.orcam.me.uk Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-09-01serial: Fix double wordShaomin Deng1-1/+1
Fix double word "start start" in comments. Signed-off-by: Shaomin Deng <dengshaomin@cdjrlc.com> Link: https://lore.kernel.org/r/20220831160934.7986-1-dengshaomin@cdjrlc.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-09-01serial: 8250_men_mcb: Remove duplicate UAPI:serial_core inclusionAndy Shevchenko1-1/+0
The UAPI serial_core.h is guaranteed to be included by in-kernel one (with the same name). Individual drivers do not need to include it explicitly. Remove it from the driver. Note, it's a single driver in the entire kernel that does this. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20220830152313.14650-1-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-08-30serial: Make ->set_termios() old ktermios constIlpo Järvinen10-14/+14
There should be no reason to adjust old ktermios which is going to get discarded anyway. Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://lore.kernel.org/r/20220816115739.10928-7-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-08-30serial: 8250: Clear dma tx_err unconditionallyIlpo Järvinen1-2/+1
No need to check non-zeroness first and then clear. Just set to zero unconditionally. Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://lore.kernel.org/r/3b885e7f-1372-3aa9-febd-34566ba25e3d@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-08-30serial: 8250: Add helper for clearing IERIlpo Järvinen1-13/+11
A number of places want to clear IER with the same CAP_UUE trick. Create a helper for that. Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://lore.kernel.org/r/20220816120759.11552-1-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-08-08Merge tag 'tty-6.0-rc1' of ↵Linus Torvalds19-227/+455
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty Pull tty / serial driver updates from Greg KH: "Here is the big set of tty and serial driver changes for 6.0-rc1. It was delayed from last week as I wanted to make sure the last commit here got some good testing in linux-next and elsewhere as it seemed to show up only late in testing for some reason. Nothing major here, just lots of cleanups from Jiri and Ilpo to make the tty core cleaner (Jiri) and the rs485 code simpler to use (Ilpo). Also included in here is the obligatory n_gsm updates from Daniel Starke and lots of tiny driver updates and minor fixes and tweaks for other smaller serial drivers. All of these have been in linux-next for a while with no reported problems" * tag 'tty-6.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (186 commits) tty: serial: qcom-geni-serial: Fix %lu -> %u in print statements tty: amiserial: Fix comment typo tty: serial: document uart_get_console() tty: serial: serial_core, reformat kernel-doc for functions Documentation: serial: link uart_ops properly Documentation: serial: move GPIO kernel-doc to the functions Documentation: serial: dedup kernel-doc for uart functions Documentation: serial: move uart_ops documentation to the struct dt-bindings: serial: snps-dw-apb-uart: Document Rockchip RV1126 serial: mvebu-uart: uart2 error bits clearing tty: serial: fsl_lpuart: correct the count of break characters serial: stm32: make info structs static to avoid sparse warnings serial: fsl_lpuart: zero out parity bit in CS7 mode tty: serial: qcom-geni-serial: Fix get_clk_div_rate() which otherwise could return a sub-optimal clock rate. serial: 8250_bcm2835aux: Add missing clk_disable_unprepare() tty: vt: initialize unicode screen buffer serial: remove VR41XX serial driver serial: 8250: lpc18xx: Remove redundant sanity check for RS485 flags serial: 8250_dwlib: remove redundant sanity check for RS485 flags dt_bindings: rs485: Correct delay values ...
2022-07-28serial: 8250_bcm2835aux: Add missing clk_disable_unprepare()Guo Mengqi1-2/+4
The error path when get clock frequency fails in bcm2835aux_serial driver does not correctly disable the clock. This flaw was found using a static analysis tool "Hulk Robot", which reported the following warning when analyzing linux-next/master: drivers/tty/serial/8250/8250_bcm2835aux.c: warning: clk_disable_unprepare_missing.cocci The cocci script checks for the existence of clk_disable_unprepare() paired with clk_prepare_enable(). Add the missing clk_disable_unprepare() to the error path. Fixes: fcc446c8aa63 ("serial: 8250_bcm2835aux: Add ACPI support") Reported-by: Hulk Robot <hulkci@huawei.com> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: Guo Mengqi <guomengqi3@huawei.com> Link: https://lore.kernel.org/r/20220715023312.37808-1-guomengqi3@huawei.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-14serial: 8250: lpc18xx: Remove redundant sanity check for RS485 flagsLino Sanfilippo1-5/+1
Before the drivers rs485_config() function is called the serial core already ensures that only one of both options RTS on send or RTS after send is set. So remove the concerning sanity check in the driver function to avoid redundancy. Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com> Link: https://lore.kernel.org/r/20220710164442.2958979-9-LinoSanfilippo@gmx.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-14serial: 8250_dwlib: remove redundant sanity check for RS485 flagsLino Sanfilippo1-8/+2
Before the drivers rs485_config() function is called the serial core already ensures that only one of both options RTS on send or RTS after send is set. So remove the concerning sanity check in the driver function to avoid redundancy. Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com> Link: https://lore.kernel.org/r/20220710164442.2958979-8-LinoSanfilippo@gmx.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-14serial: core, 8250: set RS485 termination GPIO in serial coreLino Sanfilippo1-3/+0
In serial8250_em485_config() the termination GPIO is set with the uart_port spinlock held. This is an issue if setting the GPIO line can sleep (e.g. since the concerning GPIO expander is connected via SPI or I2C). Fix this by setting the termination line outside of the uart_port spinlock in the serial core and using gpiod_set_value_cansleep() which instead of gpiod_set_value() allows it to sleep. Beside fixing the termination GPIO line setting for the 8250 driver this change also makes setting the termination GPIO generic for all UART drivers. Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com> Link: https://lore.kernel.org/r/20220710164442.2958979-4-LinoSanfilippo@gmx.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-14serial: 8250_bcm7271: Save/restore RTS in suspend/resumeDoug Berger1-6/+18
Commit 9cabe26e65a8 ("serial: 8250_bcm7271: UART errors after resuming from S2") prevented an early enabling of RTS during resume, but it did not actively restore the RTS state after resume. Fixes: 9cabe26e65a8 ("serial: 8250_bcm7271: UART errors after resuming from S2") Signed-off-by: Doug Berger <opendmb@gmail.com> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> Link: https://lore.kernel.org/r/20220714031316.404918-1-f.fainelli@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-14serial: 8250_dw: Avoid pslverr on reading empty receiver fifoVAMSHI GAJJELA1-0/+13
With PSLVERR_RESP_EN parameter set to 1, the device generates an error response when an attempt to read an empty RBR with FIFO enabled. This happens when LCR writes are ignored when UART is busy. dw8250_check_lcr() in retries to update LCR, invokes dw8250_force_idle() to clear and reset FIFO and eventually reads UART_RX causing the error. Avoid this by not reading RBR/UART_RX when no data is available. Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: VAMSHI GAJJELA <vamshigajjela@google.com> Link: https://lore.kernel.org/r/20220713131722.2316829-1-vamshigajjela@google.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-14serial: 8250: SERIAL_8250_ASPEED_VUART should depend on ARCH_ASPEEDGeert Uytterhoeven1-0/+1
The Aspeed Virtual UART is only present on Aspeed BMC platforms. Hence add a dependency on ARCH_ASPEED, to prevent asking the user about this driver when configuring a kernel without Aspeed BMC support. Reviewed-by: Jeremy Kerr <jk@ozlabs.org> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Link: https://lore.kernel.org/r/259138c372d433005b4871789ef9ee8d15320307.1657528861.git.geert+renesas@glider.be Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-14tty: 8250: Add support for Brainboxes PX cards.Cameron Williams1-0/+109
Add support for some of the Brainboxes PCIe (PX) range of serial cards, including the PX-101, PX-235/PX-246, PX-203/PX-257, PX-260/PX-701, PX-310, PX-313, PX-320/PX-324/PX-376/PX-387, PX-335/PX-346, PX-368, PX-420, PX-803 and PX-846. Signed-off-by: Cameron Williams <cang1@live.co.uk> Cc: stable <stable@kernel.org> Link: https://lore.kernel.org/r/AM5PR0202MB2564669252BDC59BF55A6E87C4879@AM5PR0202MB2564.eurprd02.prod.outlook.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-08serial: Embed rs485_supported to uart_portIlpo Järvinen7-9/+9
Embed rs485_supported to uart_port to allow serial core to tweak it as needed. Reviewed-by: Lino Sanfilippo <l.sanfilippo@kunbus.com> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://lore.kernel.org/r/20220704094515.6831-2-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-08serial: 8250_fsl: Don't report FE, PE and OE twiceUwe Kleine-König1-1/+1
Some Freescale 8250 implementations have the problem that a single long break results in one irq per character frame time. The code in fsl8250_handle_irq() that is supposed to handle that uses the BI bit in lsr_saved_flags to detect such a situation and then skip the second received character. However it also stores other error bits and so after a single frame error the character received in the next irq handling is passed to the upper layer with a frame error, too. So after a spike on the data line (which is correctly recognized as a frame error) the following valid character is thrown away, because the driver reports a frame error for that one, too. To weaken this problem restrict saving LSR to only the BI bit. Note however that the handling is still broken: - lsr_saved_flags is updated using orig_lsr which is the LSR content for the first received char, but there might be more in the FIFO, so a character is thrown away that is received later and not necessarily the one following the break. - The doubled break might be the 2nd and 3rd char in the FIFO, so the workaround doesn't catch these, because serial8250_rx_chars() doesn't handle the workaround. - lsr_saved_flags might have set UART_LSR_BI at the entry of fsl8250_handle_irq() which doesn't originate from fsl8250_handle_irq()'s "up->lsr_saved_flags |= orig_lsr & UART_LSR_BI;" but from e.g. from serial8250_tx_empty(). - For a long or a short break this isn't about two characters, but more or only a single one. Fixes: 9deaa53ac7fa ("serial: add irq handler for Freescale 16550 errata.") Acked-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Link: https://lore.kernel.org/r/20220704085119.55900-1-u.kleine-koenig@pengutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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