linux-kernel - Re: [PATCH v10 4/4] arm64: dts: qcom: qcs6490-rb3gen2-vision-mezzanine: Add vision mezzanine

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Message-ID: <99cf5f7e-43f6-4ac4-a4a2-dc731b695572@oss.qualcomm.com>
Date: Thu, 19 Dec 2024 20:06:34 +0100
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Vladimir Zapolskiy <vladimir.zapolskiy@...aro.org>,
        Vikram Sharma <quic_vikramsa@...cinc.com>, rfoss@...nel.org,
        todor.too@...il.com, bryan.odonoghue@...aro.org, mchehab@...nel.org,
        robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org,
        akapatra@...cinc.com, hariramp@...cinc.com, andersson@...nel.org,
        konradybcio@...nel.org, hverkuil-cisco@...all.nl,
        cros-qcom-dts-watchers@...omium.org, catalin.marinas@....com,
        will@...nel.org
Cc: linux-arm-kernel@...ts.infradead.org, linux-media@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, kernel@...cinc.com,
        Konrad Dybcio <konrad.dybcio@....qualcomm.com>
Subject: Re: [PATCH v10 4/4] arm64: dts: qcom:
 qcs6490-rb3gen2-vision-mezzanine: Add vision mezzanine

On 17.12.2024 3:40 PM, Vladimir Zapolskiy wrote:
> On 12/17/24 16:06, Vikram Sharma wrote:
>> The Vision Mezzanine for the RB3 ships with an imx577 camera sensor.
>> Enable the IMX577 on the vision mezzanine.
>>
>> An example media-ctl pipeline for the imx577 is:
>>
>> media-ctl --reset
>> media-ctl -v -V '"imx577 '19-001a'":0[fmt:SRGGB10/4056x3040 field:none]'
>> media-ctl -V '"msm_csiphy3":0[fmt:SRGGB10/4056x3040]'
>> media-ctl -V '"msm_csid0":0[fmt:SRGGB10/4056x3040]'
>> media-ctl -V '"msm_vfe0_rdi0":0[fmt:SRGGB10/4056x3040]'
>> media-ctl -l '"msm_csiphy3":1->"msm_csid0":0[1]'
>> media-ctl -l '"msm_csid0":1->"msm_vfe0_rdi0":0[1]'
>>
>> yavta -B capture-mplane -c -I -n 5 -f SRGGB10P -s 4056x3040 -F /dev/video0
>>
>> Signed-off-by: Hariram Purushothaman <quic_hariramp@...cinc.com>
>> Signed-off-by: Vikram Sharma <quic_vikramsa@...cinc.com>
>> Signed-off-by: Trishansh Bhardwaj <quic_tbhardwa@...cinc.com>
>> Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@...aro.org>
>> Reviewed-by: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
>> ---

[...]

>> +        rst-pins {
>> +            pins = "gpio78";
>> +            function = "gpio";
>> +            drive-strength = <2>;
>> +            bias-pull-down;
>> +            output-low;
>> +        };
> 
> I have doubts that it's proper to embed a reset gpio into driver's
> pinctrl suspend/resume power management.
> 
> Konrad, can you please confirm that it's really accepted?
> 
> I'd rather ask to remove this reset pin control.

There's certainly some appearances of this in the tree.

You could make the argument that it makes sense to prevent misconfiguration
(i.e. the bootloader may set the pin in input mode), but then the counter
argument is that the (Linux) gpiod APIs request OUT_LOW/HIGH, and we would
expect that the driver uses that if the GPIO is requested through
e.g. reset-gpios.

I'm not particularly sure what to recommend here. Krzysztof?

Konrad