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

[Arpit Saini]

Hi Dmitry,Konrad

On 7/10/2026 6:09 PM, Dmitry Baryshkov wrote:
> On Fri, Jul 10, 2026 at 05:28:04PM +0530, 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@xxxxxxxxxxxxxxxx>
>>>>>
>>>>> Enable the Qualcomm Shikra MDSS display subsystem on the Shikra CQM EVK
>>>>> board and add the DLC0697 MIPI DSI display panel node. Pin pm4125_l5
>>>>> to 1.232V with regulator-allow-set-load for DSI PHY PLL stability.
>>>>>
>>>>> Signed-off-by: Arpit Saini <arpit.saini@xxxxxxxxxxxxxxxx>
>>>>> Signed-off-by: Nabige Aala <nabige.aala@xxxxxxxxxxxxxxxx>
>>>>> ---
>>>> [...]
>>>>
>>>>> +    panel_bl_en: panel-bl-en-state {
>>>>> +        pins = "gpio91";
>>>>> +        function = "gpio";
>>>>> +        drive-strength = <2>;
>>>>> +        bias-disable;
>>>>> +        output-high;
>>>>> +    };
>>>>> +
>>>>> +    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.
> 
> Handle it from the panel driver. Also please fix your editor to prevent
> it from inserting extra empty lines.
> 

Earlier I handled it through panel driver, but this GPIO is specific to our
Qualcomm Daughter Card, it is not going to the panel connector.

In earlier panel driver version v1, I got comments on dt bindings for that,
so I modeled it like this.

as Dmitry suggested here [1], to not include backlight-en-gpios in dt bindings as it
is not panel specific.

are you suggesting any other way to do so, Please let me know.

[1] https://lore.kernel.org/all/81724048-0cb1-4305-b613-374c14df87d5@xxxxxxxxxxxxxxxx/