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authorAndy Shevchenko <andriy.shevchenko@linux.intel.com>2018-11-21 16:43:37 +0300
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2018-11-26 20:29:47 +0300
commitb413b1abeb21b4a152c0bf8d1379efa30759b6e3 (patch)
treec92825bb01d4db9d64ef906c232688331d718bf1 /drivers/acpi
parent2e6e902d185027f8e3cb8b7305238f7e35d6a436 (diff)
downloadlinux-b413b1abeb21b4a152c0bf8d1379efa30759b6e3.tar.xz
ACPI: SPCR: Consider baud rate 0 as preconfigured state
Since SPCR 1.04 [1] the baud rate of 0 means a preconfigured state of UART. Assume firmware or bootloader configures console correctly. [1]: https://docs.microsoft.com/en-us/windows-hardware/drivers/serports/serial-port-console-redirection-table Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Prarit Bhargava <prarit@redhat.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/acpi')
-rw-r--r--drivers/acpi/spcr.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/drivers/acpi/spcr.c b/drivers/acpi/spcr.c
index 9d52743080a4..c336784d0bcb 100644
--- a/drivers/acpi/spcr.c
+++ b/drivers/acpi/spcr.c
@@ -148,6 +148,13 @@ int __init acpi_parse_spcr(bool enable_earlycon, bool enable_console)
}
switch (table->baud_rate) {
+ case 0:
+ /*
+ * SPCR 1.04 defines 0 as a preconfigured state of UART.
+ * Assume firmware or bootloader configures console correctly.
+ */
+ baud_rate = 0;
+ break;
case 3:
baud_rate = 9600;
break;
@@ -196,6 +203,10 @@ int __init acpi_parse_spcr(bool enable_earlycon, bool enable_console)
* UART so don't attempt to change to the baud rate state
* in the table because driver cannot calculate the dividers
*/
+ baud_rate = 0;
+ }
+
+ if (!baud_rate) {
snprintf(opts, sizeof(opts), "%s,%s,0x%llx", uart, iotype,
table->serial_port.address);
} else {