linux-kernel - Re: [PATCH v2 6/7] drm/i915/dsi: Replace poking of CHV GPIOs behind the driver's back

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Date:   Tue, 31 Oct 2023 18:21:43 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Hans de Goede <hdegoede@...hat.com>
Cc:     Jani Nikula <jani.nikula@...el.com>,
        intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        Tvrtko Ursulin <tvrtko.ursulin@...ux.intel.com>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>
Subject: Re: [PATCH v2 6/7] drm/i915/dsi: Replace poking of CHV GPIOs behind
 the driver's back

On Tue, Oct 31, 2023 at 05:07:39PM +0100, 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:
> >> It's a dirty hack in the driver that pokes GPIO registers behind
> >> the driver's back. Moreoever it might be problematic as simultaneous
> >> I/O may hang the system, see the commit 0bd50d719b00 ("pinctrl:
> >> cherryview: prevent concurrent access to GPIO controllers") for
> >> the details. Taking all this into consideration replace the hack
> >> with proper GPIO APIs being used.
> > 
> > Ah, just realised that this won't work if it happens to request to GPIOs with
> > the same index but different communities. I will fix that in v3, but will wait
> > for Hans to test VLV and it might even work in most of the cases on CHV as it
> > seems quite unlikely that the above mentioned assertion is going to happen in
> > real life.
> 
> I have added patches 1-5 to my personal tree + a small debug patch on top
> which logs when soc_exec_opaque_gpio() actually gets called.
> 
> So these patches will now get run every time I run some tests on
> one my tablets.
> 
> I'll get back to you with testing results when I've found a device where
> the new soc_exec_opaque_gpio() actually gets called.

Thank you!

> As for the CHT support, I have not added that to my tree yet, I would
> prefer to directly test the correct/fixed patch.

Noted, I'll prepare a new version then.

-- 
With Best Regards,
Andy Shevchenko