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From:   Heiko =?ISO-8859-1?Q?St=FCbner?= <heiko@sntech.de>
To:     linux-kernel@vger.kernel.org,
        Javier Martinez Canillas <javierm@redhat.com>
Cc:     Peter Robinson <pbrobinson@gmail.com>,
        Javier Martinez Canillas <javierm@redhat.com>,
        Caleb Connolly <kc@postmarketos.org>,
        Jarrah Gosbell <kernel@undef.tools>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Martijn Braam <martijn@brixit.nl>, 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
Date:   Tue, 04 Apr 2023 09:51:11 +0200
Message-ID: <3738011.44csPzL39Z@diego>
In-Reply-To: <20230403175937.2842085-1-javierm@redhat.com>
References: <20230403175937.2842085-1-javierm@redhat.com>
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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.

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
>