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@xxxxxxxxxxxxxxx> --- drivers/acpi/spcr.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/acpi/spcr.c b/drivers/acpi/spcr.c index 9d52743080a4..ea92d88c02a6 100644 --- a/drivers/acpi/spcr.c +++ b/drivers/acpi/spcr.c @@ -148,6 +148,12 @@ 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. + */ + break; case 3: baud_rate = 9600; break; -- 2.19.1
