[PATCH v2 2/2] serial: 8250_dw: Add Sophgo SG2044 quirk

[Ilpo Järvinen]

On Mon, 21 Oct 2024, Inochi Amaoto wrote:

> On Mon, Oct 21, 2024 at 11:52:38AM +0300, Ilpo Järvinen wrote:
> > On Mon, 21 Oct 2024, Inochi Amaoto wrote:
> > 
> > > SG2044 relys on an internal divisor when calculating bitrate, which
> > > means a wrong clock for the most common bitrates. So add a quirk for
> > > this uart device to skip the set rate call and only relys on the
> > > internal UART divisor.
> > > 
> > > Signed-off-by: Inochi Amaoto <inochiama at gmail.com>
> > 
> > Reviewed-by: Ilpo Järvinen <ilpo.jarvinen at linux.intel.com>
> > 
> > I wonder though does this mean the numbers userspace can read from kernel 
> > are bogus and if something can be done about that?
> > 
> 
> I am not sure whether the clock rate can be read by the userspace.
> At least it report the right baud speed by using stty.

Okay, I meant baud & other settings. Thanks for checking it.

-- 
 i.

> Regards,
> Inochi
> 
> > 
> > > ---
> > >  drivers/tty/serial/8250/8250_dw.c | 5 +++--
> > >  1 file changed, 3 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
> > > index ab9e7f204260..51894c93c8a3 100644
> > > --- a/drivers/tty/serial/8250/8250_dw.c
> > > +++ b/drivers/tty/serial/8250/8250_dw.c
> > > @@ -750,7 +750,7 @@ static const struct dw8250_platform_data dw8250_renesas_rzn1_data = {
> > >  	.quirks = DW_UART_QUIRK_CPR_VALUE | DW_UART_QUIRK_IS_DMA_FC,
> > >  };
> > >  
> > > -static const struct dw8250_platform_data dw8250_starfive_jh7100_data = {
> > > +static const struct dw8250_platform_data dw8250_skip_set_rate_data = {
> > >  	.usr_reg = DW_UART_USR,
> > >  	.quirks = DW_UART_QUIRK_SKIP_SET_RATE,
> > >  };
> > > @@ -760,7 +760,8 @@ static const struct of_device_id dw8250_of_match[] = {
> > >  	{ .compatible = "cavium,octeon-3860-uart", .data = &dw8250_octeon_3860_data },
> > >  	{ .compatible = "marvell,armada-38x-uart", .data = &dw8250_armada_38x_data },
> > >  	{ .compatible = "renesas,rzn1-uart", .data = &dw8250_renesas_rzn1_data },
> > > -	{ .compatible = "starfive,jh7100-uart", .data = &dw8250_starfive_jh7100_data },
> > > +	{ .compatible = "sophgo,sg2044-uart", .data = &dw8250_skip_set_rate_data },
> > > +	{ .compatible = "starfive,jh7100-uart", .data = &dw8250_skip_set_rate_data },
> > >  	{ /* Sentinel */ }
> > >  };
> > >  MODULE_DEVICE_TABLE(of, dw8250_of_match);
> > > 
>