Bug 99340

Summary: no idle pc3/pc6/pc7 starting in Linux 4.7 - Macbook Air
Product: DRI Reporter: David Purton <dcpurton>
Component: DRM/IntelAssignee: Intel GFX Bugs mailing list <intel-gfx-bugs>
Status: CLOSED DUPLICATE QA Contact: Intel GFX Bugs mailing list <intel-gfx-bugs>
Severity: normal    
Priority: medium CC: dcpurton, dp-fd, edouard.thuleau, hugo, intel-gfx-bugs, matthew.d.roper
Version: DRI git   
Hardware: x86-64 (AMD64)   
OS: Linux (All)   
Whiteboard:
i915 platform: HSW i915 features: display/watermark
Attachments:
Description Flags
dmesg output for 4.10.0-rc3 drm-tip none

Description David Purton 2017-01-10 04:59:26 UTC 
Created attachment 128845 [details]
dmesg output for 4.10.0-rc3 drm-tip

Under Linux 4.6 my Macbook Air spends > 60% in pc7 state. From Linux 4.7 the system only reaches pc2. Battery life suffers significantly because of this.

I previously reported this issue at https://bugzilla.kernel.org/show_bug.cgi?id=177151 but after discussion was told to go here.


I built drm-tip 9ea6a075c23ea914695d57944c0e74cff0c6bff4 and this still exhibits the problem. I have attached dmesg with debug output for this build.


I have done a git bisect and the results are:

git checkout ed4a6a7ca853253f9b86f3005d76345482a71283~ works.
git checkout ed4a6a7ca853253f9b86f3005d76345482a71283 exhibits the problem.


I run Debian Testing and have installed OS X El Capitan 10.11.6 on the Mac partition.

Model Name: MacBook Air (11-inch, Early 2014)
Model Identifier: MacBookAir6,1
Model Number: MD712X/B
Comment 1 Jani Nikula 2017-01-10 08:24:54 UTC 
(In reply to David Purton from comment #0)
> I have done a git bisect and the results are:
> 
> git checkout ed4a6a7ca853253f9b86f3005d76345482a71283~ works.
> git checkout ed4a6a7ca853253f9b86f3005d76345482a71283 exhibits the problem.

The bad commit is

commit ed4a6a7ca853253f9b86f3005d76345482a71283
Author: Matt Roper <matthew.d.roper@intel.com>
Date:   Tue Feb 23 17:20:13 2016 -0800

    drm/i915: Add two-stage ILK-style watermark programming (v11)
Comment 2 Ville Syrjala 2017-02-17 20:00:28 UTC 
Looks like a dupe of bug 96645

*** This bug has been marked as a duplicate of bug 96645 ***
Comment 3 David Purton 2017-02-18 10:54:40 UTC 
I can confirm that the patch posted to bug 96645 fixes my problem. Thank you.

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