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Commit b413b1ab authored by Andy Shevchenko's avatar Andy Shevchenko Committed by Rafael J. Wysocki
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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: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: default avatarPrarit Bhargava <prarit@redhat.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 2e6e902d

drivers/acpi/spcr.c

+11 −0
Original line number Diff line number Diff line
@@ -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 {