diff options
| author | Andy Shevchenko <andriy.shevchenko@linux.intel.com> | 2018-11-21 15:43:37 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-02-12 19:45:59 +0100 |
| commit | 23d18c183c58e0c0ed49196f30dfaa4f6155d3b4 (patch) | |
| tree | 161d735ba0008353323d80401a7257edeab941c2 /drivers/acpi | |
| parent | cdde22f8d12e128b3db4606341bc089268794a31 (diff) | |
ACPI: SPCR: Consider baud rate 0 as preconfigured state
[ Upstream commit b413b1abeb21b4a152c0bf8d1379efa30759b6e3 ]
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'drivers/acpi')
| -rw-r--r-- | drivers/acpi/spcr.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/drivers/acpi/spcr.c b/drivers/acpi/spcr.c index 324b35bfe781..f567fa5f0148 100644 --- a/drivers/acpi/spcr.c +++ b/drivers/acpi/spcr.c @@ -148,6 +148,13 @@ int __init parse_spcr(bool earlycon) } 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 parse_spcr(bool earlycon) * 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 { |