[Regression][v3.17][3.18][3.19-rc3] drm/radeon: re-enable dpm by default on BTC

[Joseph Salisbury]

On 01/08/2015 12:48 PM, Deucher, Alexander wrote:
>> -----Original Message-----
>> From: Joseph Salisbury [mailto:joseph.salisbury at canonical.com]
>> Sent: Thursday, January 08, 2015 11:26 AM
>> To: Deucher, Alexander
>> Cc: stable at vger.kernel.org; LKML; Koenig, Christian; David Airlie; dri-devel
>> Subject: Re: [Regression][v3.17][3.18][3.19-rc3] drm/radeon: re-enable dpm
>> by default on BTC
>>
>> On 01/07/2015 09:51 PM, Deucher, Alexander wrote:
>>>> -----Original Message-----
>>>> From: Joseph Salisbury [mailto:joseph.salisbury at canonical.com]
>>>> Sent: Wednesday, January 07, 2015 5:51 PM
>>>> To: Deucher, Alexander
>>>> Cc: stable at vger.kernel.org; LKML; Koenig, Christian; David Airlie; dri-devel
>>>> Subject: [Regression][v3.17][3.18][3.19-rc3] drm/radeon: re-enable dpm
>> by
>>>> default on BTC
>>>>
>>>> Hi Alexander,
>>>>
>>>> A kernel bug report was opened against Ubuntu [0].  After a kernel
>>>> bisect, it was found that reverting the following commit resolved this bug:
>>>>
>>>> commit c08abf11900e19b14dd3a0cc3d105bd74519cd18
>>>> Author: Alex Deucher <alexander.deucher at amd.com>
>>>> Date:   Mon Jul 14 12:01:40 2014 -0400
>>>>
>>>>     drm/radeon: re-enable dpm by default on BTC
>>>>
>>>> The regression was introduced as of v3.17-rc1 and still exists in
>>>> current mainline.  It has also made it's way into the stable releases.
>>>>
>>>> I was hoping to get your feedback, since you are the patch author.  Do
>>>> you think gathering any additional data will help diagnose this issue,
>>>> or would it be best to submit a revert request?
>>>>
>>> Does revering b2dccf24e77 help?  I'd hate to revert this patch because it
>> disables power management for a whole family of chips.  If it doesn't help I'd
>> prefer to just add a quirk to disable it for the specific problematic board.
>> Commit b2dccf24e77 was added to mainline as of v3.18-rc1 and was not
>> cc'd to stable.  We are also seeing this issue in the 3.13.y stable
>> kernel, which does not have commit b2dccf24e77 applied.  However, we can
>> test reverting it in mainline?
> Nope.  Won't make a difference.  The attached patch adds a quirk list for dpm which will fix the issue for the affected boards.
>
> Alex
Thanks again for the patch, Alex.  The bug reporter has tested a 3.16
kernel with the patch and says it fixes the bug. 


>
>>> Alex
>>>
>>>> Thanks,
>>>>
>>>> Joe
>>>>
>>>> [0] http://pad.lv/1386534