Messages in this thread Patch in this message | | | From | Aleksey Makarov <> | Subject | [RFC v2 2/4] ACPI: SPCR: don't initialize baud rate | Date | Tue, 6 Dec 2016 23:58:27 +0600 |
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AppliedMicro X-Gene based boards don't use the "standard" 16550 clock rate so supplying a baud rate makes it change to a random baud rate.
I suggest to introduce a new value '0' for the "Baud Rate" field of SPCR (now this value is reserved).
This patch introduces a check for this value. In this case the code does not emit baud rate specification for initialization of the console.
Signed-off-by: Aleksey Makarov <aleksey.makarov@linaro.org> --- drivers/acpi/spcr.c | 22 +++++++++++++++------- 1 file changed, 15 insertions(+), 7 deletions(-)
diff --git a/drivers/acpi/spcr.c b/drivers/acpi/spcr.c index 6c6710b..2bf338c 100644 --- a/drivers/acpi/spcr.c +++ b/drivers/acpi/spcr.c @@ -37,7 +37,7 @@ int __init parse_spcr(bool earlycon) acpi_status status; char *uart; char *iotype; - int baud_rate; + char *baud_rate_string; int err; if (acpi_disabled) @@ -82,25 +82,33 @@ int __init parse_spcr(bool earlycon) } switch (table->baud_rate) { + case 0: + /* + * This value is not standaritzed by ACPI SPCR for now. + * It means that hardware should not be re-initialized with + * new speed. + */ + baud_rate_string = ""; + break; case 3: - baud_rate = 9600; + baud_rate_string = ",9600"; break; case 4: - baud_rate = 19200; + baud_rate_string = ",19200"; break; case 6: - baud_rate = 57600; + baud_rate_string = ",57600"; break; case 7: - baud_rate = 115200; + baud_rate_string = ",115200"; break; default: err = -ENOENT; goto done; } - snprintf(opts, sizeof(opts), "%s,%s,0x%llx,%d", uart, iotype, - table->serial_port.address, baud_rate); + snprintf(opts, sizeof(opts), "%s,%s,0x%llx%s", uart, iotype, + table->serial_port.address, baud_rate_string); pr_info("console: %s\n", opts); -- 2.10.2
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