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    SubjectRe: [Intel-gfx] [PATCH v2 6/7] drm/i915/dsi: Replace poking of CHV GPIOs behind the driver's back
    On Wed, Nov 01, 2023 at 11:20:23AM +0100, Hans de Goede wrote:
    > Hi,
    >
    > On 11/1/23 10:32, Andy Shevchenko wrote:
    > > On Tue, Oct 31, 2023 at 10:15:52PM +0100, Hans de Goede wrote:
    > >> On 10/31/23 17:07, Hans de Goede wrote:
    > >>> On 10/24/23 18:11, Andy Shevchenko wrote:
    > >>>> On Tue, Oct 24, 2023 at 06:57:38PM +0300, Andy Shevchenko wrote:
    > >
    > > ...
    > >
    > >>> As for the CHT support, I have not added that to my tree yet, I would
    > >>> prefer to directly test the correct/fixed patch.
    > >>
    > >> And I hit the "jackpot" on the first device I tried and the code needed
    > >> some fixing to actually work, so here is something to fold into v3 to
    > >> fix things:
    > >
    > > Thanks!
    > >
    > > But let me first send current v3 as it quite differs to v2 in the sense
    > > of how I do instantiate GPIO lookup tables.
    >
    > The problem is there already is a GPIO lookup table registered for
    > the "0000:00:02.0" device by intel_dsi_vbt_gpio_init() and there can
    > be only be one GPIO lookup table per device. So no matter how you
    > instantiate GPIO lookup tables it will not work.
    >
    > The solution that I chose is to not instantiate a GPIO lookup table
    > at all and instead to extend the existing table with an extra entry.
    >
    > Although thinking more about it I must admit that this is racy.
    >
    > So a better idea would be to unregister the GPIO lookup
    > table registered by intel_dsi_vbt_gpio_init() after getting
    > the GPIOs there, that would allow instantiating a new one
    > from soc_exec_opaque_gpio() as it currently does and that
    > would be race free.

    The proper solution would likely be be to pre-parse the sequences
    to determine which GPIOs are actually needed. That would also get
    rid of the bxt_gpio_table[] eyesore.

    --
    Ville Syrjälä
    Intel

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