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authorTimur Tabi <timur@codeaurora.org>2017-07-27 16:15:52 -0500
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-07-30 07:53:44 -0700
commit37ef38f3f83891a2f413fb872bae7d0f9bb95b27 (patch)
tree30ac978fba7c794ca827f8a657bda94c7f28eaaf /drivers/tty
parent520eccdfe187591a51ea9ab4c1a024ae4d0f68d9 (diff)
downloadlinux-37ef38f3f83891a2f413fb872bae7d0f9bb95b27.tar.bz2
tty: pl011: fix initialization order of QDF2400 E44
The work-around for Qualcomm Technologies QDF2400 Erratum 44 hinges on a global variable defined in the pl011 driver. The ACPI SPCR parsing code determines whether the work-around is needed, and if so, it changes the console name from "pl011" to "qdf2400_e44". The expectation is that the pl011 driver will implement the work-around when it sees the console name. The global variable qdf2400_e44_present is set when that happens. The problem is that work-around needs to be enabled when the pl011 driver probes, not when the console name is queried. However, sbsa_probe() is called before pl011_console_match(). The work-around appeared to work previously because the default console on QDF2400 platforms was always ttyAMA1. The first time sbsa_probe() is called (for ttyAMA0), qdf2400_e44_present is still false. Then pl011_console_match() is called, and it sets qdf2400_e44_present to true. All subsequent calls to sbsa_probe() enable the work-around. The solution is to move the global variable into spcr.c and let the pl011 driver query it during probe time. This works because all QDF2400 platforms require SPCR, so parse_spcr() will always be called. pl011_console_match still checks for the "qdf2400_e44" console name, but it doesn't do anything else special. Fixes: 5a0722b898f8 ("tty: pl011: use "qdf2400_e44" as the earlycon name for QDF2400 E44") Tested-by: Jeffrey Hugo <jhugo@codeaurora.org> Signed-off-by: Timur Tabi <timur@codeaurora.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
-rw-r--r--drivers/tty/serial/amba-pl011.c37
1 files changed, 19 insertions, 18 deletions
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 8a857bb34fbb..1888d168a41c 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -142,15 +142,7 @@ static struct vendor_data vendor_sbsa = {
.fixed_options = true,
};
-/*
- * Erratum 44 for QDF2432v1 and QDF2400v1 SoCs describes the BUSY bit as
- * occasionally getting stuck as 1. To avoid the potential for a hang, check
- * TXFE == 0 instead of BUSY == 1. This may not be suitable for all UART
- * implementations, so only do so if an affected platform is detected in
- * parse_spcr().
- */
-static bool qdf2400_e44_present = false;
-
+#ifdef CONFIG_ACPI_SPCR_TABLE
static struct vendor_data vendor_qdt_qdf2400_e44 = {
.reg_offset = pl011_std_offsets,
.fr_busy = UART011_FR_TXFE,
@@ -165,6 +157,7 @@ static struct vendor_data vendor_qdt_qdf2400_e44 = {
.always_enabled = true,
.fixed_options = true,
};
+#endif
static u16 pl011_st_offsets[REG_ARRAY_SIZE] = {
[REG_DR] = UART01x_DR,
@@ -2375,12 +2368,14 @@ static int __init pl011_console_match(struct console *co, char *name, int idx,
resource_size_t addr;
int i;
- if (strcmp(name, "qdf2400_e44") == 0) {
- pr_info_once("UART: Working around QDF2400 SoC erratum 44");
- qdf2400_e44_present = true;
- } else if (strcmp(name, "pl011") != 0) {
+ /*
+ * Systems affected by the Qualcomm Technologies QDF2400 E44 erratum
+ * have a distinct console name, so make sure we check for that.
+ * The actual implementation of the erratum occurs in the probe
+ * function.
+ */
+ if ((strcmp(name, "qdf2400_e44") != 0) && (strcmp(name, "pl011") != 0))
return -ENODEV;
- }
if (uart_parse_earlycon(options, &iotype, &addr, &options))
return -ENODEV;
@@ -2734,11 +2729,17 @@ static int sbsa_uart_probe(struct platform_device *pdev)
}
uap->port.irq = ret;
- uap->reg_offset = vendor_sbsa.reg_offset;
- uap->vendor = qdf2400_e44_present ?
- &vendor_qdt_qdf2400_e44 : &vendor_sbsa;
+#ifdef CONFIG_ACPI_SPCR_TABLE
+ if (qdf2400_e44_present) {
+ dev_info(&pdev->dev, "working around QDF2400 SoC erratum 44\n");
+ uap->vendor = &vendor_qdt_qdf2400_e44;
+ } else
+#endif
+ uap->vendor = &vendor_sbsa;
+
+ uap->reg_offset = uap->vendor->reg_offset;
uap->fifosize = 32;
- uap->port.iotype = vendor_sbsa.access_32b ? UPIO_MEM32 : UPIO_MEM;
+ uap->port.iotype = uap->vendor->access_32b ? UPIO_MEM32 : UPIO_MEM;
uap->port.ops = &sbsa_uart_pops;
uap->fixed_baud = baudrate;