[PATCH 0/3] drm/exynos: modify usage of wait for vblank

[Inki Dae]

2012/12/5 Prathyush K <prathyush.k at samsung.com>

> This patchset fixes a few issues with use of wait for vblank in
> exynos drm.
>
> Please apply these three patches without "drm/exynos: release fb pended by
> page flip"
> patch.
>
> Patch 1: modify wait for vsync functions to use wait queues
> This modifies the wait_for_vblank functions to use wait queues
> thus ensuring that the current task goes to sleep without taking
> up CPU while waiting.
>
> Patch 2: move wait_for_vblank to manager_ops
> Currently, we do not call wait for vblank if encoder is in DPMS_OFF
> state inside exynos_drm_encoder_complete_scanout function. This is
> because wait for vblank is treated as an overlay op.

This can be
> modified to a manager_op thus removing the above check for DPMS_OFF.
> This fixes a crash while removing a fb.
> While removing the current fb (crtc->fb == fb) the encoder
> dpms off is called and then the framebuffer is removed. So in
> this case, the wait for vblank is not called thus leading to a crash
> (since fb might get removed before dma is finished)
>
> Patch 3: do not disable crtc if already off
> We should not disable the overlay if the crtc is in DPMS_OFF state.
> Also, the disable function should not call DPMS_OFF of the crtc.
> This is required to ensure we are able to wait for vblank
> before freeing any framebuffers after disabling the crtc.
>
> With these three patches and without "drm/exynos: release fb pended by
> page flip"
> I could not find any crash/page_fault in drm with fimd/hdmi during hotplug
> and page flips.
>
>
It seems better than old one and also including some exception codes, Patch
3 we did't consider. Ok, we will test these patches and merge them instead
of old one if no problem.

Thanks,
Inki Dae


> Prathyush K (3)
>   drm/exynos: modify wait for vsync functions to use wait queues
>   drm/exynos: move wait_for_vblank to manager_ops
>   drm/exynos: do not disable crtc if already off
>
>  drivers/gpu/drm/exynos/exynos_drm_crtc.c    |    6 +++-
>  drivers/gpu/drm/exynos/exynos_drm_drv.h     |   20 ++------------
>  drivers/gpu/drm/exynos/exynos_drm_encoder.c |   15 +++--------
>  drivers/gpu/drm/exynos/exynos_drm_fimd.c    |   37
> ++++++++++++++++++--------
>  drivers/gpu/drm/exynos/exynos_drm_hdmi.c    |   22 ++++++++--------
>  drivers/gpu/drm/exynos/exynos_drm_hdmi.h    |    2 +-
>  drivers/gpu/drm/exynos/exynos_mixer.c       |   37
> +++++++++++++++++---------
>  7 files changed, 73 insertions(+), 66 deletions(-)
>
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