On Fri, 2018-02-02 at 19:18 +0000, Andy Lutomirski wrote: > On Fri, Feb 2, 2018 at 1:24 AM, Andy Lutomirski <luto@xxxxxxxxxx> wrote: > > On Thu, Feb 1, 2018 at 9:20 PM, Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> wrote: > >> Quoting Andy Lutomirski (2018-02-01 21:04:30) > >>> I got this after a recent suspend/resume: > >>> > >>> Feb 01 09:44:34 laptop systemd-logind[2412]: Lid closed. > >>> Feb 01 09:44:34 laptop systemd-logind[2412]: device-enumerator: scan all dirs > >>> Feb 01 09:44:34 laptop systemd-logind[2412]: device-enumerator: > >>> scanning /sys/bus > >>> Feb 01 09:44:34 laptop systemd-logind[2412]: device-enumerator: > >>> scanning /sys/class > >>> Feb 01 09:44:34 laptop systemd-logind[2412]: Failed to open > >>> configuration file '/etc/systemd/sleep.conf': No such file or > >>> directory > >>> Feb 01 09:44:34 laptop systemd-logind[2412]: Suspending... > >>> Feb 01 09:44:34 laptop systemd-logind[2412]: Sent message type=signal > >>> sender=n/a destination=n/a object=/org/freedesktop/login1 > >>> interface=org.freedesktop.login1.Manager member=PrepareForSleep > >>> cookie=570 reply > >>> Feb 01 09:44:34 laptop systemd-logind[2412]: Got message > >>> type=method_call sender=:1.46 destination=:1.1 > >>> object=/org/freedesktop/login1/session/_32 > >>> interface=org.freedesktop.login1.Session member=ReleaseDevice > >>> Feb 01 09:44:34 laptop systemd-logind[2412]: Sent message type=signal > >>> sender=n/a destination=:1.46 > >>> object=/org/freedesktop/login1/session/_32 > >>> interface=org.freedesktop.login1.Session member=PauseDevice cookie > >>> Feb 01 09:44:34 laptop gnome-shell[2630]: Failed to apply DRM plane > >>> transform 0: Permission denied > >>> Feb 01 09:44:34 laptop gnome-shell[2630]: drmModeSetCursor2 failed > >>> with (Permission denied), drawing cursor with OpenGL from now on > >>> > >>> But I don't see the word "cursor" in my system logs before the first > >>> suspend. What am I looking for? This is Fedora 27 running a Gnome > >>> Wayland session, but it hasn't been reinstalled in some time, so it's > >>> possible that there are some weird settings sitting around. But I did > >>> check and I have no weird i915 parameters. > >> > >> You are using gnome-shell as the display server. From that it appears to > >> have started off with a HW cursor and switched to a SW cursor after > >> suspend. Did you notice a change in behaviour? After rebooting or just > >> restarting gnome-shell? > > > > I think it's less consistently bad after a reboot before suspending. > > > >> > >>> Also, are these things potentially related: > >>> > >>> [ 3067.702527] [drm:intel_pipe_update_start [i915]] *ERROR* Potential > >>> atomic update failure on pipe A > >> > >> They are just "missed the immediate vblank for the screen update" > >> messages. Should not be related to PSR, but may cause jitter by delaying > >> the odd screen update. > > > > I just got this one, and the timestamp is at least reasonably close to > > a giant latency spike: > > > > [ 288.799654] [drm:intel_pipe_update_end [i915]] *ERROR* Atomic > > update failure on pipe A (start=31 end=32) time 15 us, min 1073, max > > 1079, scanline start 1087, end 1088 > > > >> > >>> As I'm typing this, I've seen a couple instances of what seems like a > >>> full *second* of cursor latency, but I've only gotten the potential > >>> atomic update failure once. > >>> > >>> And is there any straightforward tracing to do to distinguish between > >>> PSR exit latency and other potential sources of latency? > >> > >> It looks plausible that we could at least report how long it takes the > >> registers to reflect the change in state (but we don't). The best source > >> of information atm is /sys/kernel/debug/dri/0/i915_edp_psr_status. > > > > Hmm. > > > > I went and looked at the code, and I noticed what could be bugs or > > could (more likely) be my confusion since I don't know this code at > > all: > > > > intel_single_frame_update() does something inscrutable to me, but I > > imagine it does something that causes the next page flip to get > > noticed by the panel even with PSR on. But how does the code that > > calls it know that anything happened? (Looking at the commit history, > > maybe this is something special that's only needed on some platforms > > but doesn't replace the normal PSR exit sequence.) > > > > Perhaps more interestingly, intel_psr_flush() does this: > > > > /* By definition flush = invalidate + flush */ > > if (frontbuffer_bits) > > intel_psr_exit(dev_priv); > > > > if (!dev_priv->psr.active && !dev_priv->psr.busy_frontbuffer_bits) > > if (!work_busy(&dev_priv->psr.work.work)) > > schedule_delayed_work(&dev_priv->psr.work, > > msecs_to_jiffies(100)); > > > > I'm guessing that the idea is that we're turning off PSR because we > > want the panel to update and we expect that, in 100ms, the update will > > have hit the panel and we'll have been idle long enough for it to make > > sense to re-enter PSR. IOW, the code wants PSR to be off for at least > > 100ms and then to turn back on. But this code actually says "turn PSR > > back on in at *most* 100ms". What happens if there are two screen > > updates 99ms apart? The first one should work fine, but the next one > > will hit with 1ms left on the delayed work, and intel_psr_work() will > > get called in 1ms. There's some magic with busy_frontbuffer_bits, but > > it seems questionable to me that intel_psr_flush() clears > > busy_frontbuffer_bits and *then* calls intel_psr_exit(). > > > > Naively, I would expect that PSR needs to be kept off until the vblank > > following the page flip. > > > > Also, in intel_psr_work(), shouldn't this code: > > > > /* > > * The delayed work can race with an invalidate hence we need to > > * recheck. Since psr_flush first clears this and then reschedules we > > * won't ever miss a flush when bailing out here. > > */ > > if (dev_priv->psr.busy_frontbuffer_bits) > > goto unlock; > > > > re-arm the delayed work? > > > > Anyway, this is all on a 4.14 kernel. I should update to 4.16 and see > > what happens. > > I updated to 4.15, and the situation is much worse. With > enable_psr=1, the system survives for several seconds and then the > screen stops updating entirely. If I boot with i915.enable_psr=1, I > get to the Fedora login screen and then the system dies. If I set > enable_psr=1 using sysfs, it does a bit after the next resume. It > seems like it also sometimes hangs even worse a bit after the screen > stops updating, but it's hard to tell. The login screen freeze sounds like what I have. Does this system have DMC firmware? If yes, can you try this series https://patchwork.freedesktop.org/series/37598/. You'll only need patches 1,8,9 and 10. -DK > > I see this in my logs: > > [drm:drm_atomic_helper_wait_for_flip_done [drm_kms_helper]] *ERROR* > [CRTC:37:pipe A] flip_done timed out > > Sometimes I see this a bit later: > > [drm:drm_atomic_helper_wait_for_dependencies [drm_kms_helper]] *ERROR* > [CRTC:37:pipe A] flip_done timed out > > I'm able to get some debugging out before the system dies. I see > intel_psr_flush() getting called a bunch, and I don't see > intel_psr_invalidate() being called at all. I also see > intel_psr_work() activating psr as little as 2ms after > intel_psr_flush() finishes. So I think the code is indeed buggy or at > least questionable. I'd try to fix it (at least as well as I can > without knowing anything about how the PSR state machine actually > works), but the fact that the system hangs would make it very hard to > test. > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx > https://lists.freedesktop.org/mailman/listinfo/intel-gfx _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
