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From:   Javier Martinez Canillas <javierm@redhat.com>
To:     Martijn Braam <martijn@brixit.nl>,
        Heiko =?utf-8?Q?St=C3=BCbner?= <heiko@sntech.de>,
        linux-kernel@vger.kernel.org
Cc:     Peter Robinson <pbrobinson@gmail.com>,
        Caleb Connolly <kc@postmarketos.org>,
        Jarrah Gosbell <kernel@undef.tools>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Ondrej Jirman <megi@xff.cz>, Rob Herring <robh+dt@kernel.org>,
        Tom Fitzhenry <tom@tom-fitzhenry.me.uk>,
        devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-rockchip@lists.infradead.org
Subject: Re: [PATCH] arm64: dts: rockchip: Change serial baud rate for
 Pinephone Pro to 1.5 MB
In-Reply-To: <52d83a29-0f16-cd4c-9810-7c6bd497fe85@brixit.nl>
References: <20230403175937.2842085-1-javierm@redhat.com>
 <3738011.44csPzL39Z@diego>
 <52d83a29-0f16-cd4c-9810-7c6bd497fe85@brixit.nl>
Date:   Tue, 04 Apr 2023 13:42:36 +0200
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Martijn Braam <martijn@brixit.nl> writes:

> On 4/4/23 09:51, Heiko St=C3=BCbner 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 defau=
lt
>>> and a 'console=3DttyS2,1500000n8' kernel command line parameter is requ=
ired
>>> to have proper output for both.
>> The interesting question is always if this will break someone else's set=
up.
>> 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=
=20
> hassle

More than the extra speed is to have consistency accross all the rockchip
devices in upstream and also sync with mainline u-boot.

> of having a few devices at weird baudrates and the bootloader already
> starts outputting debug logs at 115200 baud.
>

And mine starts outputting at 1.5MBps :) I guess that there isn't a one
size fits all, so the question is whether the bikeshed color is what was
painted in all other rockchip boards or the one that Tow-Boot has chosen.

--=20
Best regards,

Javier Martinez Canillas
Core Platforms
Red Hat