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

[Sunyun Yang]

Krzysztof Kozlowski <krzk@xxxxxxxxxx> 于2026年6月25日周四 20:54写道：
>
> On 08/05/2026 15:40, syyang@xxxxxxxxxxx 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);
}


> > +     msleep(400);
> > +
> > +     dev_dbg(lt9611c->dev, "lt9611c reset");
>
> Drop such debug statements. This is some downstream, semi-useless code.
> You are not supposed to add debug to every call.
>
it will be fixed in next version.
>
> Best regards,
> Krzysztof