From: Melissa Wen <melissa.srw@gmail.com>
To: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>,
Haneen Mohammed <hamohammed.sa@gmail.com>,
Daniel Vetter <daniel@ffwll.ch>, David Airlie <airlied@linux.ie>,
Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Cc: linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
kernel-usp@googlegroups.com
Subject: [PATCH] drm/vkms: add missing drm_crtc_vblank_put to the get/put pair on flush
Date: Wed, 22 Jul 2020 08:04:11 -0300 [thread overview]
Message-ID: <20200722110411.ebkv6knvc6mzw5uf@smtp.gmail.com> (raw)
This patch adds a missing drm_crtc_vblank_put op to the pair
drm_crtc_vblank_get/put (inc/decrement counter to guarantee vblanks).
It clears the execution of the following kms_cursor_crc subtests:
1. pipe-A-cursor-[size,alpha-opaque, NxN-(on-screen, off-screen, sliding,
random, fast-moving])] - successful when running individually.
2. pipe-A-cursor-dpms passes again
3. pipe-A-cursor-suspend also passes
The issue was initially tracked in the sequential execution of IGT
kms_cursor_crc subtest: when running the test sequence or one of its
subtests twice, the odd execs complete and the pairs get stuck in an
endless wait. In the IGT code, calling a wait_for_vblank before the start
of CRC capture prevented the busy-wait. But the problem persisted in the
pipe-A-cursor-dpms and -suspend subtests.
Checking the history, the pipe-A-cursor-dpms subtest was successful when,
in vkms_atomic_commit_tail, instead of using the flip_done op, it used
wait_for_vblanks. Another way to prevent blocking was wait_one_vblank when
enabling crtc. However, in both cases, pipe-A-cursor-suspend persisted
blocking in the 2nd start of CRC capture, which may indicate that
something got stuck in the step of CRC setup. Indeed, wait_one_vblank in
the crc setup was able to sync things and free all kms_cursor_crc
subtests.
Tracing and comparing a clean run with a blocked one:
- in a clean one, vkms_crtc_atomic_flush enables vblanks;
- when blocked, only in next op, vkms_crtc_atomic_enable, the vblanks
started. Moreover, a series of vkms_vblank_simulate flow out until
disabling vblanks.
Also watching the steps of vkms_crtc_atomic_flush, when the very first
drm_crtc_vblank_get returned an error, the subtest crashed. On the other
hand, when vblank_get succeeded, the subtest completed. Finally, checking
the flush steps: it increases counter to hold a vblank reference (get),
but there isn't a op to decreased it and release vblanks (put).
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Cc: Haneen Mohammed <hamohammed.sa@gmail.com>
Signed-off-by: Melissa Wen <melissa.srw@gmail.com>
---
drivers/gpu/drm/vkms/vkms_crtc.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c
index ac85e17428f8..a99d6b4a92dd 100644
--- a/drivers/gpu/drm/vkms/vkms_crtc.c
+++ b/drivers/gpu/drm/vkms/vkms_crtc.c
@@ -246,6 +246,7 @@ static void vkms_crtc_atomic_flush(struct drm_crtc *crtc,
spin_unlock(&crtc->dev->event_lock);
+ drm_crtc_vblank_put(crtc);
crtc->state->event = NULL;
}
--
2.27.0
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next reply other threads:[~2020-07-22 11:04 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-22 11:04 Melissa Wen [this message]
2020-07-22 12:05 ` [PATCH] drm/vkms: add missing drm_crtc_vblank_put to the get/put pair on flush daniel
2020-07-22 14:06 ` Melissa Wen
2020-07-22 15:17 ` Daniel Vetter
2020-07-25 1:17 ` Sidong Yang
2020-07-25 15:57 ` Daniel Vetter
2020-07-25 17:45 ` Melissa Wen
2020-07-25 18:12 ` Daniel Vetter
2020-07-25 18:49 ` Melissa Wen
2020-07-25 19:19 ` Melissa Wen
2020-07-25 19:29 ` Melissa Wen
2020-07-26 10:26 ` Daniel Vetter
2020-07-28 16:16 ` Sidong Yang
2020-07-28 21:55 ` daniel
2020-07-29 19:09 ` Melissa Wen
2020-07-29 21:48 ` Daniel Vetter
2020-07-30 10:09 ` Melissa Wen
2020-07-31 9:08 ` daniel
2020-07-31 16:13 ` Sidong Yang
2020-07-31 16:47 ` Melissa Wen
2020-07-31 17:29 ` Leandro Ribeiro
2020-07-31 17:36 ` Leandro Ribeiro
2020-07-31 18:10 ` Leandro Ribeiro
2020-07-31 18:33 ` Daniel Vetter
2020-07-31 18:39 ` Leandro Ribeiro
2020-08-01 16:06 ` Sidong Yang
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