From 93810191f5d23652c0b8a1a9b3a4a89d6fd5063e Mon Sep 17 00:00:00 2001 From: Tony Lindgren Date: Mon, 24 Oct 2022 09:36:13 +0300 Subject: serial: 8250: omap: Fix missing PM runtime calls for omap8250_set_mctrl() 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 Reported-by: Romain Naour Reported-by: Ivaylo Dimitrov Tested-by: Ivaylo Dimitrov Signed-off-by: Tony Lindgren 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 --- drivers/tty/serial/8250/8250_omap.c | 22 ++++++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-) (limited to 'drivers/tty') diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c index 68f5a167377f..7bfa87094125 100644 --- a/drivers/tty/serial/8250/8250_omap.c +++ b/drivers/tty/serial/8250/8250_omap.c @@ -157,7 +157,11 @@ static u32 uart_read(struct uart_8250_port *up, u32 reg) return readl(up->port.membase + (reg << up->port.regshift)); } -static void omap8250_set_mctrl(struct uart_port *port, unsigned int mctrl) +/* + * Called on runtime PM resume path from omap8250_restore_regs(), and + * omap8250_set_mctrl(). + */ +static void __omap8250_set_mctrl(struct uart_port *port, unsigned int mctrl) { struct uart_8250_port *up = up_to_u8250p(port); struct omap8250_priv *priv = up->port.private_data; @@ -181,6 +185,20 @@ static void omap8250_set_mctrl(struct uart_port *port, unsigned int mctrl) } } +static void omap8250_set_mctrl(struct uart_port *port, unsigned int mctrl) +{ + int err; + + err = pm_runtime_resume_and_get(port->dev); + if (err) + return; + + __omap8250_set_mctrl(port, mctrl); + + pm_runtime_mark_last_busy(port->dev); + pm_runtime_put_autosuspend(port->dev); +} + /* * Work Around for Errata i202 (2430, 3430, 3630, 4430 and 4460) * The access to uart register after MDR1 Access @@ -343,7 +361,7 @@ static void omap8250_restore_regs(struct uart_8250_port *up) omap8250_update_mdr1(up, priv); - up->port.ops->set_mctrl(&up->port, up->port.mctrl); + __omap8250_set_mctrl(&up->port, up->port.mctrl); if (up->port.rs485.flags & SER_RS485_ENABLED) serial8250_em485_stop_tx(up); -- cgit v1.2.3