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Bug 1366872 - Backlight stutters with kernel 4.6.5+ [NEEDINFO]
Summary: Backlight stutters with kernel 4.6.5+
Keywords:
Status: CLOSED INSUFFICIENT_DATA
Alias: None
Product: Fedora
Classification: Fedora
Component: kernel
Version: 25
Hardware: x86_64
OS: Linux
unspecified
medium
Target Milestone: ---
Assignee: Kernel Maintainer List
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2016-08-13 20:33 UTC by Joe Thompson
Modified: 2017-04-28 17:14 UTC (History)
7 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed: 2017-04-28 17:14:31 UTC
jforbes: needinfo?


Attachments (Terms of Use)

Description Joe Thompson 2016-08-13 20:33:29 UTC
Description of problem: After updating to the latest packages, the backlight on my laptop screen stutters noticeably at about 5-10 Hz.  The problem goes away when I boot from the previously-installed kernel (4.5.6).


Version-Release number of selected component (if applicable): 4.6.5-200.fc23


How reproducible: 100%


Steps to Reproduce:
1. Install kernel 4.6.5-200 on affected hardware
2. Boot
3. Observe backlight brightness

Actual results: Backlight stutters noticeably


Expected results: Backlight is illuminated evenly


Additional info: My laptop is a Sager NP8651 (a rebadged Clevo P650SE) with discrete NVIDIA graphics (identified as "GM204M [GeForce GTX 970M]") alongside the built-in Intel HD Graphics 5600.  I have both nouveau and i915 loaded.

Comment 1 Joe Thompson 2016-08-26 03:40:38 UTC
Problem persists with kernel 4.6.6.

Possibly related to BZ#1358684?

Comment 2 Joe Thompson 2016-09-06 10:46:42 UTC
Still present with kernel 4.7.2-101.

Comment 3 Fedora End Of Life 2016-11-25 09:30:22 UTC
This message is a reminder that Fedora 23 is nearing its end of life.
Approximately 4 (four) weeks from now Fedora will stop maintaining
and issuing updates for Fedora 23. It is Fedora's policy to close all
bug reports from releases that are no longer maintained. At that time
this bug will be closed as EOL if it remains open with a Fedora  'version'
of '23'.

Package Maintainer: If you wish for this bug to remain open because you
plan to fix it in a currently maintained version, simply change the 'version' 
to a later Fedora version.

Thank you for reporting this issue and we are sorry that we were not 
able to fix it before Fedora 23 is end of life. If you would still like 
to see this bug fixed and are able to reproduce it against a later version 
of Fedora, you are encouraged  change the 'version' to a later Fedora 
version prior this bug is closed as described in the policy above.

Although we aim to fix as many bugs as possible during every release's 
lifetime, sometimes those efforts are overtaken by events. Often a 
more recent Fedora release includes newer upstream software that fixes 
bugs or makes them obsolete.

Comment 4 Joe Thompson 2016-12-01 17:59:07 UTC
Still happening with kernel 4.8.8 on Fedora 24.  Kernel 4.5.6 still works fine.

Comment 5 Joe Thompson 2017-01-07 16:07:48 UTC
Still occurs with kernel 4.8.15 on Fedora 25.  That said, I found a resolution: this is apparently an issue with PSR, which was enabled by default for the i915 driver in 4.6.  Setting the kernel argument i915.enable_psr=0 fixed the problem.

Comment 6 Laura Abbott 2017-01-17 01:23:10 UTC
*********** MASS BUG UPDATE **************
We apologize for the inconvenience.  There is a large number of bugs to go through and several of them have gone stale.  Due to this, we are doing a mass bug update across all of the Fedora 25 kernel bugs.
 
Fedora 25 has now been rebased to 4.9.3-200.fc25.  Please test this kernel update (or newer) and let us know if you issue has been resolved or if it is still present with the newer kernel.
 
If you have moved on to Fedora 26, and are still experiencing this issue, please change the version to Fedora 26.
 
If you experience different issues, please open a new bug report for those.

Comment 7 Joe Thompson 2017-01-30 13:06:40 UTC
See previous comment -- I found a workaround for this issue a couple of weeks ago.  Comment still applies after the rebase.

Comment 8 Justin M. Forbes 2017-04-11 14:53:59 UTC
*********** MASS BUG UPDATE **************

We apologize for the inconvenience.  There is a large number of bugs to go through and several of them have gone stale.  Due to this, we are doing a mass bug update across all of the Fedora 25 kernel bugs.

Fedora 25 has now been rebased to 4.10.9-200.fc25.  Please test this kernel update (or newer) and let us know if you issue has been resolved or if it is still present with the newer kernel.

If you have moved on to Fedora 26, and are still experiencing this issue, please change the version to Fedora 26.

If you experience different issues, please open a new bug report for those.

Comment 9 Justin M. Forbes 2017-04-28 17:14:31 UTC
*********** MASS BUG UPDATE **************
This bug is being closed with INSUFFICIENT_DATA as there has not been a response in 2 weeks. If you are still experiencing this issue, please reopen and attach the 
relevant data from the latest kernel you are running and any data that might have been requested previously.


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