Re: [PATCH v6 2/2] drm/bridge: Add Lontium LT9611C(EX/UXD) MIPI DSI to HDMI driver

[Krzysztof Kozlowski <krzk@kernel.org>]

On 26/06/2026 03:55, Sunyun Yang wrote:
> Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com> 于2026年6月25日周四 22:57写道：
>>
>> On Thu, Jun 25, 2026 at 09:26:47PM +0800, Sunyun Yang wrote:
>>> Krzysztof Kozlowski <krzk@kernel.org> 于2026年6月25日周四 21:17写道：
>>>>
>>>> On 25/06/2026 15:14, Sunyun Yang wrote:
>>>>> Krzysztof Kozlowski <krzk@kernel.org> 于2026年6月25日周四 20:54写道：
>>>>>>
>>>>>> On 08/05/2026 15:40, syyang@lontium.com wrote:
>>>>>>> +
>>>>>>> +static void lt9611c_reset(struct lt9611c *lt9611c)
>>>>>>> +{
>>>>>>> +     gpiod_set_value_cansleep(lt9611c->reset_gpio, 1);
>>>>>>> +     msleep(20);
>>>>>>> +
>>>>>>> +     gpiod_set_value_cansleep(lt9611c->reset_gpio, 0);
>>>>>>> +     msleep(20);
>>>>>>> +
>>>>>>> +     gpiod_set_value_cansleep(lt9611c->reset_gpio, 1);
>>>>>>
>>>>>> This is just plain wrong. Why do you assert, then de-assert and then
>>>>>> finally assert AGAIN the reset leaving the device in powerdown stage?
>>>>>>
>>>>> I am using software to emulate the hardware RESET button on our EVB.
>>>>> When the hardware RESET button is pressed while our chip is running,
>>>>> the signal level changes from HIGH to LOW and then back to HIGH.
>>>>>
>>>>> Of course, we can also use the following:
>>>>> static void lt9611c_reset(struct lt9611c *lt9611c)
>>>>> {
>>>>>     gpiod_set_value_cansleep(lt9611c->reset_gpio, 0);
>>>>>     msleep(50);
>>>>>     gpiod_set_value_cansleep(lt9611c->reset_gpio, 1);
>>>>>     msleep(20);
>>>>> }
>>>>
>>>> Makes no sense either and you just did not get the point and did not
>>>> answer my question. I asked WHY you leave asserted. Answer "we emulate"
>>>> is just plain wrong.
>>>>
>>>> So again please answer:
>>>>
>>>> Why do you leave device with reset asserted?
>>>>
>>>
>>>  devicetree:   reset-gpios = <&tlmm 128 GPIO_ACTIVE_HIGH>;
>>
>> It should be GPIO_ACTIVE_LOW, if the pin as active-low.
>>
> 
> Yes, I understand that.
> 
> I used GPIO_ACTIVE_HIGH intentionally, because I did not want to
> modify the existing reset-gpios = <&tlmm 128 GPIO_ACTIVE_HIGH>
> property in the lontium-lt9611.yaml device tree file that was

The example there does not matter. You must write correct driver.

That is it.

If you cannot bring the arguments why reset must be asserted for the
normal operation of the device, then this is the end of discussion.


Best regards,
Krzysztof