On 31 October 2017 at 14:55, Geert Uytterhoeven geert@linux-m68k.org wrote:
Hi Rafael, Tero,
CC pinchartl, dri-devel
On Tue, Oct 31, 2017 at 2:10 PM, Geert Uytterhoeven geert@linux-m68k.org wrote:
CC linux-renesas-soc
On Tue, Oct 31, 2017 at 2:09 PM, Geert Uytterhoeven geert@linux-m68k.org wrote:
On Tue, Oct 31, 2017 at 12:27 AM, Rafael J. Wysocki rjw@rjwysocki.net wrote:
On Monday, October 30, 2017 11:19:08 AM CET Rafael J. Wysocki wrote:
On Mon, Oct 30, 2017 at 8:10 AM, Tero Kristo t-kristo@ti.com wrote:
The recent change to the PM QoS framework to introduce a proper no constraint value overlooked to handle the devices which don't implement PM QoS OPS. Runtime PM is one of the more severely impacted subsystems, failing every attempt to runtime suspend a device. This leads into some nasty second level issues like probe failures and increased power consumption among other things.
Oh, that's bad.
Sorry about breaking it and thanks for the fix!
Fix this by adding a proper return value for devices that don't implement PM QoS implicitly.
Fixes: 0cc2b4e5a020 ("PM / QoS: Fix device resume latency PM QoS") Signed-off-by: Tero Kristo t-kristo@ti.com Cc: Rafael J. Wysocki rafael.j.wysocki@intel.com
Applied.
And pushed to Linus.
I'm afraid it is not sufficient.
Commit 0cc2b4e5a020fc7f ("PM / QoS: Fix device resume latency PM QoS") introduced two issues on Renesas platforms:
After boot up, many devices have changed their state from "suspended" to "active", according to /sys/kernel/debug/pm_genpd/pm_genpd_summary (comparing that file across boots is one of my standard tests). Interestingly, doing a system suspend/resume cycle restores their state to "suspended".
During system suspend, the following warning is printed on r8a7791/koelsch:
i2c-rcar e6530000.i2c: runtime PM trying to suspend device butactive child
I've just bisected a seemingly unrelated issue to the same commit. On Salvator-XS with R-Car H3, initialization of the rcar-du driver now takes more than 1 minute due to flip_done time outs, while it took 0.12s before:
[ 3.015035] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013). [ 3.021721] [drm] No driver support for vblank timestamp query. [ 13.280738] [drm:drm_atomic_helper_wait_for_flip_done] *ERROR*
[CRTC:58:crtc-3] flip_done timed out [ 23.520707] [drm:drm_atomic_helper_commit_cleanup_done] *ERROR* [CRTC:58:crtc-3] flip_done timed out [ 33.760708] [drm:drm_atomic_helper_wait_for_flip_done] *ERROR* [CRTC:58:crtc-3] flip_done timed out [ 44.000755] [drm:drm_atomic_helper_commit_cleanup_done] *ERROR* [CRTC:58:crtc-3] flip_done timed out [ 44.003597] Console: switching to colour frame buffer device 128x48 [ 54.240707] [drm:drm_atomic_helper_wait_for_flip_done] *ERROR* [CRTC:58:crtc-3] flip_done timed out [ 64.480706] [drm:drm_atomic_helper_commit_cleanup_done] *ERROR* [CRTC:58:crtc-3] flip_done timed out [ 64.544876] rcar-du feb00000.display: fb0: frame buffer device [ 64.552013] [drm] Initialized rcar-du 1.0.0 20130110 for feb00000.display on minor 0 [ 64.559873] [drm] Device feb00000.display probed
Commit 2a9a86d5c81389cd ("PM / QoS: Fix default runtime_pm device resume latency") fixes the second issue, but not the first.
... nor the third.
Reverting commits 2a9a86d5c81389cd ("PM / QoS: Fix default runtime_pm device resume latency") and 0cc2b4e5a020fc7f ("PM / QoS: Fix device resume latency PM QoS") fixes both.
... all three.
Do you have a clue? Thanks!
As I didn't have the time to review the original commit, before it got pushed as a fix, I am planning to review it now instead.
A vague guess is that the genpd governor prevents the device from being suspended. That was also the most tricky part of the changes from the original commit, which is causing problems.
I get back to this when I have reviewed it more thoroughly.
Kind regards Uffe