diff options
| author | Chen Pei <cp0613@linux.alibaba.com> | 2025-09-13 15:08:15 +0800 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2025-09-22 19:13:08 +0200 |
| commit | 4d330fe54145ecfbb657ac01a554fdedf3c1927e (patch) | |
| tree | d540a33873da17a7258bd8fbda1b291444f55137 | |
| parent | bf4206d7ac278bbd1eb2cf02d25486c2cc61b298 (diff) | |
ACPI: SPCR: Support Precise Baud Rate field
The Microsoft Serial Port Console Redirection (SPCR) specification
revision 1.09 comprises additional field: Precise Baud Rate [1].
It is used to describe non-traditional baud rates (such as those
used by high-speed UARTs).
It contains a specific non-zero baud rate which overrides the value
of the Configured Baud Rate field. If this field is zero or not
present, Configured Baud Rate is used.
Link: https://learn.microsoft.com/en-us/windows-hardware/drivers/serports/serial-port-console-redirection-table [1]
Signed-off-by: Chen Pei <cp0613@linux.alibaba.com>
Link: https://patch.msgid.link/20250913070815.16758-1-cp0613@linux.alibaba.com
[ rjw: Corrected typo in the subject ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
| -rw-r--r-- | drivers/acpi/spcr.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/drivers/acpi/spcr.c b/drivers/acpi/spcr.c index 208d6bbc65e0..d4d52d5e9016 100644 --- a/drivers/acpi/spcr.c +++ b/drivers/acpi/spcr.c @@ -149,7 +149,15 @@ int __init acpi_parse_spcr(bool enable_earlycon, bool enable_console) goto done; } - switch (table->baud_rate) { + /* + * SPCR 1.09 defines Precise Baud Rate Filed contains a specific + * non-zero baud rate which overrides the value of the Configured + * Baud Rate field. If this field is zero or not present, Configured + * Baud Rate is used. + */ + if (table->precise_baudrate) + baud_rate = table->precise_baudrate; + else switch (table->baud_rate) { case 0: /* * SPCR 1.04 defines 0 as a preconfigured state of UART. |