Re: [Intel-gfx] [PATCH v5 4/4] drm/dp: Revert "drm/dp: Introduce EDID-based quirks"

From: Jani Nikula <jani.nikula@intel.com>
To: Lyude Paul <lyude@redhat.com>, intel-gfx@lists.freedesktop.org
Cc: David Airlie <airlied@linux.ie>,
	Chris Wilson <chris@chris-wilson.co.uk>,
	Vasily Khoruzhick <anarsoul@gmail.com>,
	Dave Airlie <airlied@redhat.com>,
	Wambui Karuga <wambui.karugax@gmail.com>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	Lucas De Marchi <lucas.demarchi@intel.com>,
	Maxime Ripard <mripard@kernel.org>,
	Sean Paul <seanpaul@chromium.org>,
	"open list:DRM DRIVERS" <dri-devel@lists.freedesktop.org>,
	open list <linux-kernel@vger.kernel.org>
Subject: Re: [Intel-gfx] [PATCH v5 4/4] drm/dp: Revert "drm/dp: Introduce EDID-based quirks"
Date: Mon, 11 Jan 2021 21:08:48 +0200	[thread overview]
Message-ID: <87eeirwatb.fsf@intel.com> (raw)
In-Reply-To: <87h7nnwauw.fsf@intel.com>

On Mon, 11 Jan 2021, Jani Nikula <jani.nikula@intel.com> wrote:
> On Thu, 07 Jan 2021, Lyude Paul <lyude@redhat.com> wrote:
>> This reverts commit 0883ce8146ed6074c76399f4e70dbed788582e12. Originally
>> these quirks were added because of the issues with using the eDP
>> backlight interfaces on certain laptop panels, which made it impossible
>> to properly probe for DPCD backlight support without having a whitelist
>> for panels that we know have working VESA backlight control interfaces
>> over DPCD. As well, it should be noted it was impossible to use the
>> normal sink OUI for recognizing these panels as none of them actually
>> filled out their OUIs, hence needing to resort to checking EDIDs.
>>
>> At the time we weren't really sure why certain panels had issues with
>> DPCD backlight controls, but we eventually figured out that there was a
>> second interface that these problematic laptop panels actually did work
>> with and advertise properly: Intel's proprietary backlight interface for
>> HDR panels. So far the testing we've done hasn't brought any panels to
>> light that advertise this interface and don't support it properly, which
>> means we finally have a real solution to this problem.
>>
>> As a result, we now have no need for the force DPCD backlight quirk, and
>> furthermore this also removes the need for any kind of EDID quirk
>> checking in DRM. So, let's just revert it for now since we were the only
>> driver using this.
>>
>> v3:
>> * Rebase
>> v2:
>> * Fix indenting error picked up by checkpatch in
>>   intel_edp_init_connector()
>>
>> Signed-off-by: Lyude Paul <lyude@redhat.com>
>> Acked-by: Jani Nikula <jani.nikula@intel.com>
>
> Still stands.

PS. You'll still need drm or drm-misc maintainer ack if you want to
merge this through drm-intel-next.

-- 
Jani Nikula, Intel Open Source Graphics Center
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