Bug 110303 - [regression, bisected] vt console display doesn't update with psr
Summary: [regression, bisected] vt console display doesn't update with psr
Status: NEW
Alias: None
Product: DRI
Classification: Unclassified
Component: DRM/Intel (show other bugs)
Version: XOrg git
Hardware: x86-64 (AMD64) Linux (All)
: low normal
Assignee: Intel GFX Bugs mailing list
QA Contact: Intel GFX Bugs mailing list
URL:
Whiteboard: Triaged, ReadyForDev
Keywords:
Depends on:
Blocks:
 
Reported: 2019-04-01 23:05 UTC by Carl Michal
Modified: 2019-06-18 19:41 UTC (History)
3 users (show)

See Also:
i915 platform: BDW
i915 features: display/PSR


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Description Carl Michal 2019-04-01 23:05:19 UTC
On a Dell XPS13 9343, with kernels newer than 4.17, a vt switch (CTRL-ALT-Fn) to a console vt has become unusable if psr is enabled. Any console output only appears after a long delay (or in more recent kernels only after a vt switch away and back).

I bisected to this commit:
75cbec033c08f6d41c4775784f66ab860d02a6b5

In current drm-tip the problem is still there. If I comment out setting
EDP_PSR_DEBUG_MASK_DISP_REG_WRITE in intel_psr.c
then the vt behaves as expected.

This is a Broadwell machine:
#lspci:
00:02.0 VGA compatible controller: Intel Corporation HD Graphics 5500 (rev 09)

I realize that psr isn't exactly supported on BDW - though I've been using it for years and have never seen the lockups that people complained about that led to its being turned off by default.
Comment 1 Lakshmi 2019-04-02 07:36:31 UTC
Jose, any comments here?
Comment 2 Lakshmi 2019-04-12 10:22:25 UTC
Dk, any comments here?
Comment 3 Jose Roberto de Souza 2019-04-12 14:45:12 UTC
As said we don't support PSR on BDW by default, so lowering the importance.
Comment 4 Dhinakaran Pandiyan 2019-04-12 20:58:34 UTC
(In reply to Carl Michal from comment #0)
> On a Dell XPS13 9343, with kernels newer than 4.17, a vt switch
> (CTRL-ALT-Fn) to a console vt has become unusable if psr is enabled. Any
> console output only appears after a long delay (or in more recent kernels
> only after a vt switch away and back).
> 
> I bisected to this commit:
> 75cbec033c08f6d41c4775784f66ab860d02a6b5
> 
> In current drm-tip the problem is still there. If I comment out setting
> EDP_PSR_DEBUG_MASK_DISP_REG_WRITE in intel_psr.c
> then the vt behaves as expected.
> 
The reason we made that change was to not cause PSR exit on any display register write, we want PSR exits to be predictable. If this issue only occurs on BDW, it looks like the workaround we have in intel_psr_flush() isn't working on BDW or for some reason console updates aren't calling intel_psr_flush().


> This is a Broadwell machine:
> #lspci:
> 00:02.0 VGA compatible controller: Intel Corporation HD Graphics 5500 (rev
> 09)
> 
> I realize that psr isn't exactly supported on BDW - though I've been using
> it for years and have never seen the lockups that people complained about
> that led to its being turned off by default.

I have seen a couple of other bug reports on BDW too (flip timeouts). So, we won't be able to enable PSR on BDW by default until we fix all known issues.
Comment 5 Jose Roberto de Souza 2019-06-18 19:41:56 UTC
Carl can you give a try with this patch https://bugs.freedesktop.org/show_bug.cgi?id=110799#c5 or just use drm-tip as that patch was merged.


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