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

[Sunyun Yang]

Maxime Ripard <mripard@xxxxxxxxxx> 于2026年6月26日周五 17:53写道：
>
> On Fri, Jun 26, 2026 at 05:45:08PM +0800, Sunyun Yang wrote:
> > Maxime Ripard <mripard@xxxxxxxxxx> 于2026年6月26日周五 17:31写道：
> > >
> > > On Fri, Jun 26, 2026 at 05:05:38PM +0800, Sunyun Yang wrote:
> > > > Sunyun Yang <syyang@xxxxxxxxxxx> 于2026年6月26日周五 16:40写道：
> > > >
> > > > >
> > > > > Maxime Ripard <mripard@xxxxxxxxxx> 于2026年6月26日周五 16:26写道：
> > > > > >
> > > > > > On Fri, Jun 26, 2026 at 04:13:18PM +0800, Sunyun Yang wrote:
> > > > > > > Maxime Ripard <mripard@xxxxxxxxxx> 于2026年6月26日周五 15:49写道：
> > > > > > > >
> > > > > > > > On Fri, Jun 26, 2026 at 10:15:03AM +0800, Sunyun Yang wrote:
> > > > > > > > > Krzysztof Kozlowski <krzk@xxxxxxxxxx> 于2026年6月25日周四 21:51写道：
> > > > > > > > > >
> > > > > > > > > > On 25/06/2026 15:40, Sunyun Yang wrote:
> > > > > > > > > > > Sunyun Yang <syyang@xxxxxxxxxxx> 于2026年6月25日周四 21:26写道：
> > > > > > > > > > >>
> > > > > > > > > > >> Krzysztof Kozlowski <krzk@xxxxxxxxxx> 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@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);
> > > > > > > > > > >>>> }
> > > > > > > > > > >>>
> > > > > > > > > > >>> 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>;
> > > > > > > > > > >>
> > > > > > > > > > >> GPIO_ACTIVE_HIGH:
> > > > > > > > > > >>
> > > > > > > > > > >> gpiod_set_value_cansleep(lt9611c->reset_gpio, 0);   ------   reset pin
> > > > > > > > > > >> is Low level : Clear the register configuration in the chip to stop
> > > > > > > > > > >> the chip from working.
> > > > > > > > > > >>
> > > > > > > > > > >> gpiod_set_value_cansleep(lt9611c->reset_gpio, 1);   ------  reset pin
> > > > > > > > > > >> is high level:  The chip resumes operation.
> > > > > > > > > > >>
> > > > > > > > > > >>
> > > > > > > > > > >
> > > > > > > > > > > Our purpose is: pull the level low to clear the register configuration
> > > > > > > > > > > in the chip, and then pull it high to allow the MCU inside the chip to
> > > > > > > > > > > re‑initialize the registers.
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > And you do completely opposite... so that confirms your code is just wrong.
> > > > > > > > > >
> > > > > > > > >
> > > > > > > > > The lontium-lt9611.yaml uses GPIO_ACTIVE_HIGH. I am just following the
> > > > > > > > > rule of this device tree. If I modify the device tree to use
> > > > > > > > > GPIO_ACTIVE_LOW,
> > > > > > > > > and use the following code in my driver, then my driver would be correct.
> > > > > > > > > However, would the existing kernel drivers lontium-lt9611uxc.c and
> > > > > > > > > lontium-lt9611.c be affected?
> > > > > > > >
> > > > > > > > It might, but then it's a DT problem. The GPIO API for drivers always
> > > > > > > > considers the logical state of a GPIO, so if you need to assert a
> > > > > > > > signal, you'll always need to set 1. That's what Krzysztof was trying to
> > > > > > > > explain.
> > > > > > > >
> > > > > > > > The DT will provide with GPIO_ACTIVE_* how that logical state translates
> > > > > > > > to a physical GPIO state.
> > > > > > > >
> > > > > > > > If the DT says that this particular GPIO is active-high, then it means
> > > > > > > > that we need to set the GPIO to 1 to assert reset. Now of course, it
> > > > > > > > might not make sense for the controller itself, but it might for the
> > > > > > > > board if there's a GPIO inverter in the middle for example.
> > > > > > > >
> > > > > > > > Anyway, in the case you're raising, the issue definitely lies in the DT,
> > > > > > > > and that's what would need to be fixed.
> > > > > > > >
> > > > > > > > I also wouldn't be too concerned about lontium-lt9611.yaml, it's just an
> > > > > > > > example.
> > > > > > > >
> > > > > > > > Maxime
> > > > > > >
> > > > > > > thanks Maxime, I will modify this code in the next version of the
> > > > > > > driver, and I hope you can accept these changes.
> > > > > > >
> > > > > > > Maxime:
> > > > > > > I have another question I would like to ask you
> > > > > > > regarding sashiko-bot@xxxxxxxxxx. Since sashiko-bot sometimes has
> > > > > > > opinions that differ from yours, whose advice should I follow?
> > > > > > >
> > > > > > > If I do not adopt sashiko-bot's suggestions, will my patches still be
> > > > > > > accepted into the upstream Linux kernel?
> > > > > >
> > > > > > I can't give a blanket answer. It depends on what you ignore exactly.
> > > > > >
> > > > >
> > > > > Okay, another question: sashiko-bot is an AI bot. Are its review
> > > > > comments optional, or must they be followed?
> > > > >
> > > >
> > > > For example, in my driver, there is a function for upgrading the chip
> > > > firmware. During debugging or production, upgrading the chip firmware
> > > > will acquire a lock, which will block the DRM callback and affect
> > > > display. It will be fine after the upgrade is completed and some
> > > > devices are restarted. As long as there is no subsequent upgrade,
> > > > display can work normally.
> > > >
> > > > From a purely software perspective, the AI bot considered this
> > > > approach unacceptable and proposed synchronizing the pre-upgrade state
> > > > to the DRM framework. From my personal perspective, I think the AI
> > > > bot's suggestion would only make my driver more complex and redundant.
> > > > Do you think I need to adopt the AI bot's suggestion?
> > >
> > > You're right it's wrong, but there's also no reason to allow that
> > > firmware upgrade during the driver lifetime either through a debugfs
> > > file. So you should get rid of the debugfs file and now you won't have
> > > to bother with that comment anymore.
> > >
> > > > In addition, if I follow the AI bot's suggestion, the
> > > > lontium-lt9611uxc.c and lontium-lt8713sx.c drivers that have been
> > > > merged into the upstream Linux kernel would not meet the AI bot's
> > > > requirements.
> > >
> > > Maybe, but it's not relevant either way. These drivers are merged, yours
> > > isn't. Feel free to fix these if you spot any issue though.
> > >
> > > > When I get a reviewer's Reviewed-by flag, can I ignore the opinion of
> > > > sashiko-bot (the AI bot)?
> > >
> > > Again, it depends on the comment. If you feel like one can be ignored,
> > > you should at least argue why.
> > >
> >
> > sashiko‑bot (AI bot) does not communicate or interact with me.
> > Even if I explain the reasons, the AI bot never replies to me, and it
> > only sends its review comments to me alone.
>
> Then put it into the cover letter?
>

thanks Maxime,
I will modify the driver patch, include the relevant explanation in
the cover letter, and then submit it.



> > If I do not make changes according to the AI bot's suggestions, will
> > that affect my driver being merged into the upstream Linux kernel? I
> > would like to know the answer to this question.
>
> I told you twice already.