Re: [igt-dev] [PATCH v2 1/2] tests/kms_vrr: Use atomic API for page flip

Modem, Bhanuprakash
2020-08-14T04:04:42Z

> -----Original Message-----
> From: Navare, Manasi <manasi.d.navare@intel.com>
> Sent: Friday, August 14, 2020 4:51 AM
> To: Modem, Bhanuprakash <bhanuprakash.modem@intel.com>
> Cc: igt-dev@lists.freedesktop.org; Harry Wentland
> <harry.wentland@amd.com>; Nicholas Kazlauskas
> <nicholas.kazlauskas@amd.com>
> Subject: Re: [PATCH v2 1/2] tests/kms_vrr: Use atomic API for page flip
>
> On Thu, Aug 06, 2020 at 12:02:04AM -0700, Modem, Bhanuprakash wrote:
> > > -----Original Message-----
> > > From: Navare, Manasi <manasi.d.navare@intel.com>
> > > Sent: Thursday, August 6, 2020 12:41 AM
> > > To: Modem, Bhanuprakash <bhanuprakash.modem@intel.com>
> > > Cc: igt-dev@lists.freedesktop.org; Harry Wentland
> > > <harry.wentland@amd.com>; Nicholas Kazlauskas
> > > <nicholas.kazlauskas@amd.com>
> > > Subject: Re: [PATCH v2 1/2] tests/kms_vrr: Use atomic API for page
> flip
> > >
> > > On Thu, Aug 06, 2020 at 12:05:05AM +0530, Bhanuprakash Modem wrote:
> > > > We should avoid using drmModePageFlip as it'll only be used for
> > > > legacy drivers, instead, use igt_display_commit_atomic() API to
> > > > page flip for atomic display code path.
> > > >
> > > > v2:
> > > > * Look for the page flip event not for the vblank event (Nicholas)
> > >
> > > Where have you done this change to wait for page flip event instead of
> > > vblank event?
> > > I thought we would need to change the function get_vblank_event_ns()
> for
> > > this, I dont see
> > > that change below, may be I am missing something?
> > [Bhanu] I think no need to change the logic in get_vblank_event_ns().
> May be we can have extra check (like "ev.base.type == event") to make sure
> we are reading the correct event.
> >
> > Call flow:
> > 1) drmWaitVBlank --> get_vblank_event_ns(): will get the
> DRM_EVENT_VBLANK event timestamp
> > 2) igt_display_commit_atomic(DRM_MODE_PAGE_FLIP_EVENT) -->
> get_vblank_event_ns(): will get the DRM_EVENT_FLIP_COMPLETE event
> timestamp
>
> Okay yes this makes sense now, would be better to explain this call flow
> in the get_vblank_event_ns()
> function header somewhere and yes good idea to make its name generic,
> get_kernel_event_ns()
> and explain that it could be either vblank event or flip event with the
> above call flow.
> And also explain why we should care here for flip event rather than
> vblank.
> Because vblank is triggered after each frame but depending on vblank
> evasion time
> flip might or might not happen in that same frame, so capture flip event.
[Bhanu]
Sure, I'll float a new revision by making these changes. But these changes don't impact the functionality, so we are good to go for testing.

@Nicholas: did you get a chance to test this patch on AMD h/w?
>
> Manasi
>
> >
> > Yeah, we can rename the get_vblank_event_ns() in a generic way like
> get_event_ns()
> > >
> > > @Nicholas, have you tested the AMD stack with the page flip event
> > > timestamp deltas
> > > instead of the vblank event timetsmap deltas and does that work?
> > >
> > > Manasi
> > >
> > > > * Fix to flip with different FBs (Bhanu)
> > > >
> > > > Cc: Harry Wentland <harry.wentland@amd.com>
> > > > Cc: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
> > > > Cc: Manasi Navare <manasi.d.navare@intel.com>
> > > > Signed-off-by: Bhanuprakash Modem <bhanuprakash.modem@intel.com>
> > > > ---
> > > > tests/kms_vrr.c | 45 +++++++++++++++++----------------------------
> > > > 1 file changed, 17 insertions(+), 28 deletions(-)
> > > >
> > > > diff --git a/tests/kms_vrr.c b/tests/kms_vrr.c
> > > > index 559ef203..b433a12e 100644
> > > > --- a/tests/kms_vrr.c
> > > > +++ b/tests/kms_vrr.c
> > > > @@ -47,6 +47,7 @@ typedef struct range {
> > > > typedef struct data {
> > > > igt_display_t display;
> > > > int drm_fd;
> > > > +igt_plane_t *primary;
> > > > igt_fb_t fb0;
> > > > igt_fb_t fb1;
> > > > } data_t;
> > > > @@ -126,11 +127,11 @@ static range_t get_vrr_range(data_t *data,
> > > igt_output_t *output)
> > > > }
> > > >
> > > > /* Returns a suitable vrr test frequency. */
> > > > -static uint32_t get_test_rate_ns(data_t *data, igt_output_t
> *output)
> > > > +static uint64_t get_test_rate_ns(data_t *data, igt_output_t
> *output)
> > > > {
> > > > drmModeModeInfo *mode = igt_output_get_mode(output);
> > > > range_t range;
> > > > -uint32_t vtest;
> > > > +uint64_t vtest;
> > > >
> > > > /*
> > > > * The frequency with the fastest convergence speed should be
> > > > @@ -165,7 +166,6 @@ static void set_vrr_on_pipe(data_t *data, enum
> pipe
> > > pipe, bool enabled)
> > > > static void prepare_test(data_t *data, igt_output_t *output, enum
> pipe
> > > pipe)
> > > > {
> > > > drmModeModeInfo mode = *igt_output_get_mode(output);
> > > > -igt_plane_t *primary;
> > > > cairo_t *cr;
> > > >
> > > > /* Reset output */
> > > > @@ -189,8 +189,8 @@ static void prepare_test(data_t *data,
> igt_output_t
> > > *output, enum pipe pipe)
> > > > igt_put_cairo_ctx(cr);
> > > >
> > > > /* Take care of any required modesetting before the test begins. */
> > > > -primary = igt_output_get_plane_type(output,
> DRM_PLANE_TYPE_PRIMARY);
> > > > -igt_plane_set_fb(primary, &data->fb0);
> > > > +data->primary = igt_output_get_plane_type(output,
> > > DRM_PLANE_TYPE_PRIMARY);
> > > > +igt_plane_set_fb(data->primary, &data->fb0);
> > > >
> > > > igt_display_commit_atomic(&data->display,
> > > > DRM_MODE_ATOMIC_ALLOW_MODESET, NULL);
> > > > @@ -210,32 +210,25 @@ wait_for_vblank(data_t *data, enum pipe pipe)
> > > > return get_vblank_event_ns(data);
> > > > }
> > > >
> > > > -/* Performs an asynchronous non-blocking page-flip on a pipe. */
> > > > -static int
> > > > -do_flip(data_t *data, enum pipe pipe_id, igt_fb_t *fb)
> > > > +/* Performs an atomic non-blocking page-flip on a pipe. */
> > > > +static void
> > > > +do_flip(data_t *data, igt_fb_t *fb)
> > > > {
> > > > -igt_pipe_t *pipe = &data->display.pipes[pipe_id];
> > > > -int ret;
> > > > +int ret = 0;
> > > >
> > > > igt_set_timeout(1, "Scheduling page flip\n");
> > > >
> > > > -/*
> > > > - * Only the legacy flip ioctl supports async flips.
> > > > - * It's also non-blocking, but returns -EBUSY if flipping too fast.
> > > > - * 2x monitor tests will need async flips in the atomic API.
> > > > - */
> > > > +igt_plane_set_fb(data->primary, fb);
> > > > +
> > > > do {
> > > > -ret = drmModePageFlip(data->drm_fd, pipe->crtc_id,
> > > > - fb->fb_id,
> > > > - DRM_MODE_PAGE_FLIP_EVENT |
> > > > - DRM_MODE_PAGE_FLIP_ASYNC,
> > > > - data);
> > > > +igt_display_commit_atomic(&data->display,
> > > > + DRM_MODE_ATOMIC_NONBLOCK |
> > > > + DRM_MODE_PAGE_FLIP_EVENT,
> > > > + data);
> > > > } while (ret == -EBUSY);
> > > >
> > > > igt_assert_eq(ret, 0);
> > > > igt_reset_timeout();
> > > > -
> > > > -return 0;
> > > > }
> > > >
> > > > /*
> > > > @@ -246,11 +239,6 @@ do_flip(data_t *data, enum pipe pipe_id,
> igt_fb_t
> > > *fb)
> > > > * can arbitrarily restrict the bounds further than the absolute
> > > > * min and max range. But VRR is really about extending the flip
> > > > * to prevent stuttering or to match a source content rate.
> > > > - *
> > > > - * The only way to "present" at a fixed rate like userspace in a
> vendor
> > > > - * neutral manner is to do it with async flips. This avoids the
> need
> > > > - * to wait for next vblank and it should eventually converge at the
> > > > - * desired rate.
> > > > */
> > > > static uint32_t
> > > > flip_and_measure(data_t *data, igt_output_t *output, enum pipe
> pipe,
> > > > @@ -269,7 +257,7 @@ flip_and_measure(data_t *data, igt_output_t
> *output,
> > > enum pipe pipe,
> > > > int64_t diff_ns;
> > > >
> > > > front = !front;
> > > > -do_flip(data, pipe, front ? &data->fb1 : &data->fb0);
> > > > +do_flip(data, front ? &data->fb1 : &data->fb0);
> > > >
> > > > vblank_ns = get_vblank_event_ns(data);
> > > > diff_ns = rate_ns - (vblank_ns - last_vblank_ns);
> > > > @@ -359,6 +347,7 @@ test_basic(data_t *data, enum pipe pipe,
> > > igt_output_t *output, uint32_t flags)
> > > > "Target VRR off threshold exceeded, result was %u%%\n",
> > > > result);
> > > >
> > > > +igt_plane_set_fb(data->primary, NULL);
> > > > igt_remove_fb(data->drm_fd, &data->fb1);
> > > > igt_remove_fb(data->drm_fd, &data->fb0);
> > > > }
> > > > --
> > > > 2.20.1
> > > >