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

[Martijn Braam <martijn@brixit.nl>]

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@redhat.com>
>> ---
>>
>> 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
>>
>
>
>