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

Kazlauskas, Nicholas
2020-08-04T16:10:47Z

Sorry for the delay on checking this.

I've given it a spin and on Raven/Navi I see that before applying the
patches I get SUCCESS for all 3 subtests but after applying them every
test fails.

Patch 1 is what breaks it, but it's hard to say whether this is a test
bug or AMDGPU driver bug from initial investigation.

I'm seeing that the vblank_ns = last_vblank_ns so I think we're still on
the same frame when we get the event back.

I would think this would affect userspace behavior but adaptive sync
works fine on this kernel for games and benchmarks.

Not sure if what I was doing with wait_for_vblank works is actually
waiting for the page flip event from the driver or just the vblank
event. We want to be comparing the delta between the page-flip events.

Regards,
Nicholas Kazlauskas

On 2020-08-03 6:17 p.m., Navare, Manasi wrote:
>
> @Harry and @Nicholas, could you run kms_vrr IGT with this patch on AMD
> to see that with teh atomic API, it doesnt break VRR on AMD?
>
> Regards
> Manasi
>
> On Wed, Jul 01, 2020 at 09:16:59PM -0700, Modem, Bhanuprakash wrote:
>>> -----Original Message-----
>>> From: Navare, Manasi D <manasi.d.navare@intel.com>
>>> Sent: Wednesday, June 3, 2020 12:41 AM
>>> To: Modem, Bhanuprakash <bhanuprakash.modem@intel.com>
>>> Cc: igt-dev@lists.freedesktop.org; harry.wentland@amd.com;
>>> nicholas.kazlauskas@amd.com; Kiran, Pichika Uday
>>> <pichika.uday.kiran@intel.com>
>>> Subject: Re: [RFC PATCH 1/2] tests/kms_vrr: Use atomic API for page flip
>>>
>>> On Mon, May 11, 2020 at 11:56:46AM +0530, bhanuprakash.modem@intel.com
>>> wrote:
>>>> From: Bhanuprakash Modem <bhanuprakash.modem@intel.com>
>>>>
>>>> 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.
>>>>
>>>> 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>
>>>
>>> I have tested this on i915 and the page flips are captured correctly with
>>> non blocking page flip requests using atomic_commit call.
>>>
>>> @Harry, @Nicholas could you test this on AMD driver to make
>>> sure its not breaking anything?
>> [Bhanu]
>> @Harry, @Nicholas did you get a chance to check this patch?
>>>
>>> Manasi
>>>
>>>> ---
>>>> tests/kms_vrr.c | 39 ++++++++++-----------------------------
>>>> 1 file changed, 10 insertions(+), 29 deletions(-)
>>>>
>>>> diff --git a/tests/kms_vrr.c b/tests/kms_vrr.c
>>>> index 73115fef..0fe28931 100644
>>>> --- a/tests/kms_vrr.c
>>>> +++ b/tests/kms_vrr.c
>>>> @@ -126,11 +126,11 @@ 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
>>>> @@ -210,32 +210,18 @@ 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
>>>> +/* Performs an atomic non-blocking page-flip on a pipe. */
>>>> +static void
>>>> do_flip(data_t *data, enum pipe pipe_id, igt_fb_t *fb)
>>>> {
>>>> -igt_pipe_t *pipe = &data->display.pipes[pipe_id];
>>>> -int ret;
>>>> -
>>>> 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.
>>>> - */
>>>> -do {
>>>> -ret = drmModePageFlip(data->drm_fd, pipe->crtc_id,
>>>> - fb->fb_id,
>>>> - DRM_MODE_PAGE_FLIP_EVENT |
>>>> - DRM_MODE_PAGE_FLIP_ASYNC,
>>>> - data);
>>>> -} while (ret == -EBUSY);
>>>> -
>>>> -igt_assert_eq(ret, 0);
>>>> -igt_reset_timeout();
>>>> +igt_display_commit_atomic(&data->display,
>>>> + DRM_MODE_ATOMIC_NONBLOCK |
>>>> + DRM_MODE_PAGE_FLIP_EVENT,
>>>> + NULL);
>>>>
>>>> -return 0;
>>>> +igt_reset_timeout();
>>>> }
>>>>
>>>> /*
>>>> @@ -246,11 +232,6 @@ 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,
>>>> @@ -271,7 +252,7 @@ flip_and_measure(data_t *data, igt_output_t *output,
>>> enum pipe pipe,
>>>> front = !front;
>>>> do_flip(data, pipe, front ? &data->fb1 : &data->fb0);
>>>>
>>>> -vblank_ns = get_vblank_event_ns(data);
>>>> +vblank_ns = wait_for_vblank(data, pipe);
>>>> diff_ns = rate_ns - (vblank_ns - last_vblank_ns);
>>>> last_vblank_ns = vblank_ns;
>>>>
>>>> --
>>>> 2.24.1.1.gb6d4d82bd5
>>>>