Re: [PATCH v2 2/4] arm64: dts: qcom: shikra-cqm-evk: Enable display and add ili7807s panel

[Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>]

On 7/10/26 1:58 PM, Arpit Saini wrote:
> Hi Konrad,
> 
> On 7/10/2026 2:31 PM, Arpit Saini wrote:
>> Hi Konrad,
>>
>> On 7/6/2026 3:33 PM, Konrad Dybcio wrote:
>>> On 7/6/26 8:04 AM, Nabige Aala wrote:
>>>> From: Arpit Saini <arpit.saini@oss.qualcomm.com>

[...]

>>>> +    panel_bl_en_suspend: panel-bl-en-suspend-state {
>>>> +        pins = "gpio91";
>>>> +        function = "gpio";
>>>> +        drive-strength = <2>;
>>>> +        bias-pull-down;
>>>> +        output-low;
>>>> +    };
>>> output-foo isn't necessary, the panel driver will assert it as
>>> necessary
>>>
>>> Konrad
>>
>> Ack, thanks for pointing out.
>>
>> Arpit
>>
> I just checked,
> 
> Normally the backlight EN pin is controlled by a backlight driver.
> 
> However, this panel uses MIPI DCS based backlight control with no
> 
> separate backlight driver. Since there is no driver to assert gpio91,
> 
> we control it via the panel's pinctrl default state..
> 
> So this is platform specific pin , we need this to enable/disable
> 
> the backlight.

Why would the backlight state be so tightly defined by the panel?
Disabling or adjusting the backlight level without shutting down
the panel is a perfectly valid use case.

Take a look at pwm-backlight or gpio-backlight.

Konrad

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