Messages in this thread | | | Date | Mon, 9 Jan 2023 08:22:36 +0100 | Subject | Re: [PATCH] serial: atmel: fix incorrect baudrate setup | From | Tobias Schramm <> |
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Am 09.01.23 um 08:07 schrieb Greg Kroah-Hartman: > On Mon, Jan 09, 2023 at 08:02:00AM +0100, Tobias Schramm wrote: >> Commit ba47f97a18f2 ("serial: core: remove baud_rates when serial console >> setup") changed uart_set_options to select the correct baudrate >> configuration based on the absolute error between requested baudrate and >> available standard baudrate settings. >> Prior to that commit the baudrate was selected based on which predefined >> standard baudrate did not exceed the requested baudrate. >> This change of selection logic was never reflected in the atmel serial >> driver. Thus the comment left in the atmel serial driver is no longer >> accurate. >> Additionally the manual rounding up described in that comment and applied >> via (quot - 1) requests an incorrect baudrate. Since uart_set_options uses >> tty_termios_encode_baud_rate to determine the appropriate baudrate flags >> this can cause baudrate selection to fail entirely because >> tty_termios_encode_baud_rate will only select a baudrate if relative error >> between requested and selected baudrate does not exceed +/-2%. >> Fix that by requesting actual, exact baudrate used by the serial. >> >> Signed-off-by: Tobias Schramm <t.schramm@manjaro.org> >> --- > What commit id does this fix? Please list that as a the "Fixes:" tag.
Commit ba47f97a18f2 ("serial: core: remove baud_rates when serial console setup") is the one that breaks the assumptions made in the driver. I'll send a v2 and include that.
> > Also, does this need to go to older/stable kernels? Yep, this should go to older kernels as a fix, too. > > thanks, > > greg k-h
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