[Intel-gfx] [Acer Aspire V5-573G] Black screen on boot due to low brightness setting

[Aaron Lu]

On 11/14/2013 02:24 PM, Jani Nikula wrote:
> 
> Hi Mario -
> 
> On Wed, 13 Nov 2013, Mario Kleinsasser <mario.kleinsasser+linux-kernel at gmail.com> wrote:
>> In the last three weeks I've narrowed down the bug described in the
>> subject through Ubuntu launchpad. My new Laptop (Acer Aspire V5-573G)
>> with new Haswell CPU shows a black screen on reboot because the
>> brightness is on zero level. I verified this behaviour with the latest
>> mainline kernel from
>> http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.12-trusty/
> 
> Thanks for the report. I'll have to ask you to try some kernels, and
> logs running them, etc. that IMHO are better suited attached to a bug
> report than cluttered on the mailing list. Please file a bug on
> DRM/Intel at [1]. Reference your mail. There it will also pop up in our
> bug team's searches, and has a better chance of not falling under the
> radar. :)
> 
>> I have done the bisect process and tracked the bug down to the
>> following commit.
>>
>> For explanation:
>> good commit means: The laptop starts with display brightness on full
>> power, but low(er) resolution and the Fn+ keys are not working
>> bad commit means: The laptop starts with black display (0 brightness),
>> Fn+ keys are working and you can level up the brightness trough the
>> Fn+ keys. The resolution is the native LCD hardware display resolution
>>
>> Bisect output:
>>
>> 70b12bb415463c1bd146b67c5fbf6784fd046ad9 is the first bad commit
>> commit 70b12bb415463c1bd146b67c5fbf6784fd046ad9
>> Author: Paulo Zanoni <paulo.r.zanoni at intel.com>
>> Date: Tue Nov 20 13:32:30 2012 -0200
>>
>>     drm/i915: promote Haswell to full support
>>
>>     Since it should be working a little bit better now.
>>
>>     Signed-off-by: Paulo Zanoni <paulo.r.zanoni at intel.com>
>>     Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
>>
>> :040000 040000 f93a7761de2157a8be61f20ca9a5499264bb5c55
>> 1fed098470278830f06b0bca1706f61ba231d38d M drivers
>>
>> For the full bug report and the additional hardware information please
>> see https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1239183
>>
>> I've also searched the LKML and maybe this bug could be in conjunction
>> with http://marc.info/?t=137837786100005&r=1&w=2
> 
> You only start using our driver for Haswell from the first "bad" commit,
> and then we actually serve the ACPI opregion backlight requests. This
> explains the backlight Fn keys in your good/bad commit explanations. If
> this is a known bug in ACPI, it also explains the zero backlight.

It's actually a bug in firmware and we try to work around it in ACPI
video module :-)

>From the description it indeed seems to be the firmware initial zero
brightness level bug to me.

Thanks,
Aaron

> 
> There's two branches I'd like you to try:
> 
> 1) linux-next branch of [2]. This should contain a fix for some ACPI
>    initial backlight issues. (CC Aaron for this.)
> 
> 2) backlight-rework branch of [3]. What the branch name says.
> 
> Please add drm.debug=0xe module parameter and attach full dmesg to the
> bug.
> 
> 
> Thanks,
> Jani.
> 
> 
> [1] https://bugs.freedesktop.org/enter_bug.cgi?product=DRI
> [2] http://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git
> [3] git://gitorious.org/jani/drm.git
> 
> 
>