Re: [PATCH] Revert "drm/i915: skip modeset if compatible for everyone."

Maarten Lankhorst
2015-12-08T08:10:54Z

Op 19-11-15 om 10:05 schreef Jani Nikula:
> On Thu, 19 Nov 2015, Jani Nikula <jani.nikula@intel.com> wrote:
>> This reverts
>>
>> commit 6764e9f8724f1231b4deac53b9a82286ac0830e7
>> Author: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
>> Date: Thu Aug 27 15:44:06 2015 +0200
>>
>> drm/i915: skip modeset if compatible for everyone.
>>
>> Bring back the i915.fastboot module parameter, disabled by default, due
>> to backlight regression on Chromebook Pixel 2015.
>>
>> Apparently the firmware of the Chromebook in question enables the panel
>> but disables backlight to avoid a brief garbage scanout upon loading the
>> kernel/module. With fastboot, we leave the backlight untouched, in this
>> case disabled. The user would have to do a modeset (i.e. not just crank
>> up the brightness) to enable the backlight.
>>
>> There is no clean fix readily available, so get back to the drawing
>> board by reverting.
>>
>> [N.B. The reference below is for when the thread was included on public
>> lists, and some of the context had already been dropped by then.]
>>
>> Reported-and-tested-by: Olof Johansson <olof@lixom.net>
>> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
>> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
>> References: http://marc.info/?i=CAKMK7uES7xk05ki92oeX6gmvZWAh9f2vL7yz=6T+fGK9J3X7cQ@mail.gmail.com
>> Fixes: 6764e9f8724f ("drm/i915: skip modeset if compatible for everyone.")
>> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> Pushed to drm-intel-fixes with IRC acks from Daniel and Maarten (*). I
> took the liberty of adding Tested-by from Olof, as he reported reverting
> the bad commit fixes the issue for him, and it's a clean revert.
>
I want to enable fast modeset again in the future, but that depends on chromebook pixel being fixed.
How do you want to handle fixing up the backlight on this machine?