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

[Joseph Salisbury]

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?

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