VKMS needs vblank interrupts enabled to capture CRC. When vblank is
disabled, tests like kms_cursor_crc and kms_pipe_crc_basic getting stuck
waiting for a capture that will not occur until vkms wakes up. This patch
adds a helper to set composer and ensure that vblank remains enabled as
long as the CRC capture is needed.
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 on preparing for
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. Besides, other alternatives to force enabling vblanks or prevent
disabling them such as calling drm_crtc_put_vblank or modeset_enables
before commit_planes + offdelay = 0, also unlock all subtests executions.
Finally, due to vkms's dependence on vblank interruptions to perform
tasks, this patch uses refcount to ensure that vblanks happen when
enabling composer and while crc capture is needed.
Cc: Rodrigo Siqueira <[email protected]>
Cc: Haneen Mohammed <[email protected]>
Co-developed-by: Sidong Yang <[email protected]>
Signed-off-by: Sidong Yang <[email protected]>
Co-developed-by: Daniel Vetter <[email protected]>
Signed-off-by: Daniel Vetter <[email protected]>
Signed-off-by: Melissa Wen <[email protected]>
---
drivers/gpu/drm/vkms/vkms_composer.c | 20 +++++++++++++++++---
drivers/gpu/drm/vkms/vkms_drv.h | 1 +
2 files changed, 18 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/vkms/vkms_composer.c b/drivers/gpu/drm/vkms/vkms_composer.c
index b8b060354667..e2ac2b9759bf 100644
--- a/drivers/gpu/drm/vkms/vkms_composer.c
+++ b/drivers/gpu/drm/vkms/vkms_composer.c
@@ -233,6 +233,22 @@ int vkms_verify_crc_source(struct drm_crtc *crtc, const char *src_name,
return 0;
}
+void vkms_set_composer(struct vkms_output *out, bool enabled)
+{
+ bool old_enabled;
+
+ if (enabled)
+ drm_crtc_vblank_get(&out->crtc);
+
+ spin_lock_irq(&out->lock);
+ old_enabled = out->composer_enabled;
+ out->composer_enabled = enabled;
+ spin_unlock_irq(&out->lock);
+
+ if (old_enabled)
+ drm_crtc_vblank_put(&out->crtc);
+}
+
int vkms_set_crc_source(struct drm_crtc *crtc, const char *src_name)
{
struct vkms_output *out = drm_crtc_to_vkms_output(crtc);
@@ -241,9 +257,7 @@ int vkms_set_crc_source(struct drm_crtc *crtc, const char *src_name)
ret = vkms_crc_parse_source(src_name, &enabled);
- spin_lock_irq(&out->lock);
- out->composer_enabled = enabled;
- spin_unlock_irq(&out->lock);
+ vkms_set_composer(out, enabled);
return ret;
}
diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
index f4036bb0b9a8..2cc86d08bd4e 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.h
+++ b/drivers/gpu/drm/vkms/vkms_drv.h
@@ -142,6 +142,7 @@ int vkms_verify_crc_source(struct drm_crtc *crtc, const char *source_name,
size_t *values_cnt);
/* Composer Support */
+void vkms_set_composer(struct vkms_output *output, bool enabled);
void vkms_composer_worker(struct work_struct *work);
#endif /* _VKMS_DRV_H_ */
--
2.27.0
On Thu, Aug 06, 2020 at 08:17:05AM -0300, Melissa Wen wrote:
> VKMS needs vblank interrupts enabled to capture CRC. When vblank is
> disabled, tests like kms_cursor_crc and kms_pipe_crc_basic getting stuck
> waiting for a capture that will not occur until vkms wakes up. This patch
> adds a helper to set composer and ensure that vblank remains enabled as
> long as the CRC capture is needed.
>
> 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 on preparing for
> 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. Besides, other alternatives to force enabling vblanks or prevent
> disabling them such as calling drm_crtc_put_vblank or modeset_enables
> before commit_planes + offdelay = 0, also unlock all subtests executions.
>
> Finally, due to vkms's dependence on vblank interruptions to perform
> tasks, this patch uses refcount to ensure that vblanks happen when
> enabling composer and while crc capture is needed.
For next time around, please include a patch changelog here so people know
what was changed, and why. E.g.
v2:
- extract a vkms_set_composer helper
- fix vblank refcounting for the disabling case
>
> Cc: Rodrigo Siqueira <[email protected]>
> Cc: Haneen Mohammed <[email protected]>
> Co-developed-by: Sidong Yang <[email protected]>
> Signed-off-by: Sidong Yang <[email protected]>
> Co-developed-by: Daniel Vetter <[email protected]>
> Signed-off-by: Daniel Vetter <[email protected]>
Nah that's a bit too much credit for me, I'll get the r-b tag. You &
Sidong figured this story out, so I'd use Co-debugged-by: Sidong here for
credits.
> Signed-off-by: Melissa Wen <[email protected]>
> ---
> drivers/gpu/drm/vkms/vkms_composer.c | 20 +++++++++++++++++---
> drivers/gpu/drm/vkms/vkms_drv.h | 1 +
> 2 files changed, 18 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/vkms/vkms_composer.c b/drivers/gpu/drm/vkms/vkms_composer.c
> index b8b060354667..e2ac2b9759bf 100644
> --- a/drivers/gpu/drm/vkms/vkms_composer.c
> +++ b/drivers/gpu/drm/vkms/vkms_composer.c
> @@ -233,6 +233,22 @@ int vkms_verify_crc_source(struct drm_crtc *crtc, const char *src_name,
> return 0;
> }
>
> +void vkms_set_composer(struct vkms_output *out, bool enabled)
Since this isn't yet used outside of this file I'd just make this static.
Writeback connector support can then add the prototype in the header. With
that
Reviewed-by: Daniel Vetter <[email protected]>
Please include that tag for revision 3.
Cheers, Daniel
> +{
> + bool old_enabled;
> +
> + if (enabled)
> + drm_crtc_vblank_get(&out->crtc);
> +
> + spin_lock_irq(&out->lock);
> + old_enabled = out->composer_enabled;
> + out->composer_enabled = enabled;
> + spin_unlock_irq(&out->lock);
> +
> + if (old_enabled)
> + drm_crtc_vblank_put(&out->crtc);
> +}
> +
> int vkms_set_crc_source(struct drm_crtc *crtc, const char *src_name)
> {
> struct vkms_output *out = drm_crtc_to_vkms_output(crtc);
> @@ -241,9 +257,7 @@ int vkms_set_crc_source(struct drm_crtc *crtc, const char *src_name)
>
> ret = vkms_crc_parse_source(src_name, &enabled);
>
> - spin_lock_irq(&out->lock);
> - out->composer_enabled = enabled;
> - spin_unlock_irq(&out->lock);
> + vkms_set_composer(out, enabled);
>
> return ret;
> }
> diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
> index f4036bb0b9a8..2cc86d08bd4e 100644
> --- a/drivers/gpu/drm/vkms/vkms_drv.h
> +++ b/drivers/gpu/drm/vkms/vkms_drv.h
> @@ -142,6 +142,7 @@ int vkms_verify_crc_source(struct drm_crtc *crtc, const char *source_name,
> size_t *values_cnt);
>
> /* Composer Support */
> +void vkms_set_composer(struct vkms_output *output, bool enabled);
> void vkms_composer_worker(struct work_struct *work);
>
> #endif /* _VKMS_DRV_H_ */
> --
> 2.27.0
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch