Re: [PATCH] arm64: dts: rockchip: Change serial baud rate for Pinephone Pro to 1.5 MB

[Martijn Braam]

On 4/4/23 09:51, Heiko Stübner wrote:
> Hi,
>
> Am Montag, 3. April 2023, 19:59:37 CEST schrieb Javier Martinez Canillas:
> > This baud rate is set for the device by mainline u-boot and is also what
> > is set in the Pinebook Pro Device Tree, which is a device similar to the
> > PinePhone Pro but with a different form factor.
> >
> > Otherwise, the baud rate of the firmware and Linux don't match by default
> > and a 'console=ttyS2,1500000n8' kernel command line parameter is required
> > to have proper output for both.
> The interesting question is always if this will break someone else's setup.
> I've never really understood the strange setting of 1.5MBps, but on the
> other hand it _is_ a reality on most boards.

It breaks my device test setup at least. The extra speed isn't worth the 
hassle
of having a few devices at weird baudrates and the bootloader already
starts outputting debug logs at 115200 baud.

> Personally I don't care that much either way, but would like a comment
> from the other people working on that device - if possible.
>
> I guess if we don't hear anything, I'll apply it nevertheless at some point
>
>
> Heiko
>
>
> > Signed-off-by: Javier Martinez Canillas <javierm@xxxxxxxxxx>
> > ---
> >
> > I tried to instead get rid of the baud rate altogether, as suggested by
> > Peter Robinson. AFAIU that should just pick whatever bad rate has been
> > using by the early console.
> >
> > But neither using 'stdout-path = "serial2" nor 'stdout-path = &uart2'
> > worked for me.
> >
> > In both cases I didn't have any output unless setting a baud rate using
> > the 'console='param.
> >
> >   arch/arm64/boot/dts/rockchip/rk3399-pinephone-pro.dts | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/arch/arm64/boot/dts/rockchip/rk3399-pinephone-pro.dts b/arch/arm64/boot/dts/rockchip/rk3399-pinephone-pro.dts
> > index a0795a2b1cb1..6bbe65bd5bd4 100644
> > --- a/arch/arm64/boot/dts/rockchip/rk3399-pinephone-pro.dts
> > +++ b/arch/arm64/boot/dts/rockchip/rk3399-pinephone-pro.dts
> > @@ -26,7 +26,7 @@ aliases {
> >   	};
> >   
> >   	chosen {
> > -		stdout-path = "serial2:115200n8";
> > +		stdout-path = "serial2:1500000n8";
> >   	};
> >   
> >   	gpio-keys {
> >
> > base-commit: 3adf89324a2b2a9dbc2c12d8895021e7e34e3346