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

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Message-ID: <87eeirwatb.fsf@intel.com>
Date:   Mon, 11 Jan 2021 21:08:48 +0200
From:   Jani Nikula <jani.nikula@...el.com>
To:     Lyude Paul <lyude@...hat.com>, intel-gfx@...ts.freedesktop.org
Cc:     thaytan@...aisin.net, Vasily Khoruzhick <anarsoul@...il.com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        Ville Syrjälä <ville.syrjala@...ux.intel.com>,
        Imre Deak <imre.deak@...el.com>,
        Chris Wilson <chris@...is-wilson.co.uk>,
        Dave Airlie <airlied@...hat.com>,
        Sean Paul <seanpaul@...omium.org>,
        Lucas De Marchi <lucas.demarchi@...el.com>,
        Uma Shankar <uma.shankar@...el.com>,
        Manasi Navare <manasi.d.navare@...el.com>,
        Gwan-gyeong Mun <gwan-gyeong.mun@...el.com>,
        Ankit Nautiyal <ankit.k.nautiyal@...el.com>,
        Wambui Karuga <wambui.karugax@...il.com>,
        José Roberto de Souza <jose.souza@...el.com>,
        Pankaj Bharadiya <pankaj.laxminarayan.bharadiya@...el.com>,
        Lee Shawn C <shawn.c.lee@...el.com>,
        Anshuman Gupta <anshuman.gupta@...el.com>,
        "open list\:DRM DRIVERS" <dri-devel@...ts.freedesktop.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 4/4] drm/dp: Revert "drm/dp: Introduce EDID-based quirks"

On Mon, 11 Jan 2021, Jani Nikula <jani.nikula@...el.com> wrote:
> On Thu, 07 Jan 2021, Lyude Paul <lyude@...hat.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@...hat.com>
>> Acked-by: Jani Nikula <jani.nikula@...el.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