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

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Message-ID: <ZTfssxRsrDxhzSQ6@smile.fi.intel.com>
Date:   Tue, 24 Oct 2023 19:11:31 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Jani Nikula <jani.nikula@...el.com>,
        intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Cc:     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>,
        Hans de Goede <hdegoede@...hat.com>
Subject: Re: [PATCH v2 6/7] drm/i915/dsi: Replace poking of CHV GPIOs behind
 the driver's back

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.

-- 
With Best Regards,
Andy Shevchenko