[igt-dev] [PATCH v2] tests/kms_flip: Discard any stale event at each retry

[Mark Yacoub]

Applied. thanks!

On Tue, Oct 26, 2021 at 4:41 AM Petri Latvala <petri.latvala at intel.com> wrote:
>
> On Fri, Sep 24, 2021 at 02:39:29PM -0400, Mark Yacoub wrote:
> > From: Mark Yacoub <markyacoub at google.com>
> >
> > [Why]
> > On slower devices, non blocking do_page_flip followed by wait_for_events
> > does not finish fast enough to send an event to be consumed by wait_for_events.
> > Instead, wait_for_events ends up finding an unconsumed event from a
> > previous do_page_flip (i.e. a skipped preceding subtest) and signals
> > that the userspace is ready to do another do_page_flip while the first
> > one hasn't finished yet, resulting in an EBUSY.
> >
> > [How]
> > At the beginning of every test running on crtc set, check for any stale
> > events and consume them so the kernel has no pending events.
> >
> > Fixes: flip-vs-suspend and flip-vs-suspend-interruptible.
> > Tested on ChromeOS Volteer(i915-TGL) and Trogdor(msm)
> >
> > Changes since v1:
> > 1. Update the discard_any_stale_events timeout
> > 2. Correct a debug message
> > 3. use C-style comments
> >
> > Signed-off-by: Mark Yacoub <markyacoub at chromium.org>
>
> Looks like Arek's comments have been addressed, and this LGTM.
>
> Reviewed-by: Petri Latvala <petri.latvala at intel.com>
>
>
> > ---
> >  tests/kms_flip.c | 23 +++++++++++++++++++++++
> >  1 file changed, 23 insertions(+)
> >
> > diff --git a/tests/kms_flip.c b/tests/kms_flip.c
> > index b4836a44..73a8e636 100755
> > --- a/tests/kms_flip.c
> > +++ b/tests/kms_flip.c
> > @@ -1265,6 +1265,26 @@ static bool needs_retry_after_link_reset(struct udev_monitor *mon)
> >       return hotplug_detected;
> >  }
> >
> > +static void discard_any_stale_events() {
> > +     fd_set fds;
> > +     FD_ZERO(&fds);
> > +     FD_SET(drm_fd, &fds);
> > +     struct timeval timeout = { .tv_sec = 0, .tv_usec = 20000 };
> > +     int ret = select(drm_fd + 1, &fds, NULL, NULL, &timeout);
> > +
> > +     if (ret > 0) {
> > +             drmEventContext evctx;
> > +             memset(&evctx, 0, sizeof evctx);
> > +             evctx.version = 2;
> > +             igt_info("Stale Event found - Discarding now\n");
> > +             drmHandleEvent(drm_fd, &evctx);
> > +     }
> > +     else {
> > +             igt_debug("No stale events found\n");
> > +     }
> > +}
> > +
> > +
> >  static void __run_test_on_crtc_set(struct test_output *o, int *crtc_idxs,
> >                                  int crtc_count, int duration_ms)
> >  {
> > @@ -1315,6 +1335,9 @@ static void __run_test_on_crtc_set(struct test_output *o, int *crtc_idxs,
> >               kmstest_dump_mode(&o->kmode[i]);
> >
> >  retry:
> > +     /* Discard any pending event that hasn't been consumed from a previous retry or subtest. */
> > +     discard_any_stale_events();
> > +
> >       memset(&o->vblank_state, 0, sizeof(o->vblank_state));
> >       memset(&o->flip_state, 0, sizeof(o->flip_state));
> >       o->flip_state.name = "flip";
> > --
> > 2.33.0.685.g46640cef36-goog
> >