diff mbox series

[v1] ACPI: SPCR: Consider baud rate 0 as preconfigured state

Message ID 20181121093142.2363-1-andriy.shevchenko@linux.intel.com (mailing list archive)
State Superseded, archived
Headers show
Series [v1] ACPI: SPCR: Consider baud rate 0 as preconfigured state | expand

Commit Message

Andy Shevchenko Nov. 21, 2018, 9:31 a.m. UTC
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>
---
 drivers/acpi/spcr.c | 6 ++++++
 1 file changed, 6 insertions(+)

Comments

Andy Shevchenko Nov. 21, 2018, 11:37 a.m. UTC | #1
On Wed, Nov 21, 2018 at 11:31:42AM +0200, Andy Shevchenko wrote:
> 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>
> ---
>  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.
> +		 */

Oops, it works by lack.
Here we need to assign baud rate to 0.
I'll send v2 soon.

> +		break;
>  	case 3:
>  		baud_rate = 9600;
>  		break;
> -- 
> 2.19.1
>
diff mbox series

Patch

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;