Hi Kieran,
On Thursday 13 Jul 2017 16:51:18 Kieran Bingham wrote:
> Hi Laurent,
>
> I've just seen Maxime's latest series "[PATCH 0/4] drm/sun4i: Fix a register
> access bug" and it relates directly to a comment I had in this patch:
> On 12/07/17 17:35, Kieran Bingham wrote:
>
> > On 28/06/17 19:50, Laurent Pinchart wrote:
> >> Commit 52055bafa1ff ("drm: rcar-du: Move plane commit code from CRTC
> >> start to CRTC resume") changed the order of the plane commit and CRTC
> >> enable operations to accommodate the runtime PM requirements. However,
> >> this introduced corruption in the first displayed frame, as the CRTC is
> >> now enabled without any plane configured. On Gen2 hardware the first
> >> frame will be black and likely unnoticed, but on Gen3 hardware we end up
> >> starting the display before the VSP compositor, which is more
> >> noticeable.
> >>
> >> To fix this, revert the order of the commit operations back, and handle
> >> runtime PM requirements in the CRTC .atomic_begin() and .atomic_enable()
> >> helper operation handlers.
> >>
> >> Signed-off-by: Laurent Pinchart
> >> <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>
> >
> > I only have code reduction or comment suggestions below - so either with
> > or without those changes, feel free to add my:
> >
> > Reviewed-by: Kieran Bingham <kieran.bingham+renesas@xxxxxxxxxxxxxxxx>
> >
> >> ---
> >>
> >> drivers/gpu/drm/rcar-du/rcar_du_crtc.c | 66 +++++++++++++++++-----------
> >> drivers/gpu/drm/rcar-du/rcar_du_crtc.h | 4 +--
> >> drivers/gpu/drm/rcar-du/rcar_du_kms.c | 2 +-
> >> 3 files changed, 43 insertions(+), 29 deletions(-)
[snip]
> >> diff --git a/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> >> b/drivers/gpu/drm/rcar-du/rcar_du_kms.c index 82b978a5dae6..c2f382feca07
> >> 100644
> >> --- a/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> >> +++ b/drivers/gpu/drm/rcar-du/rcar_du_kms.c
> >> @@ -255,9 +255,9 @@ static void rcar_du_atomic_commit_tail(struct
> >> drm_atomic_state *old_state)>>
> >> /* Apply the atomic update. */
> >> drm_atomic_helper_commit_modeset_disables(dev, old_state);
> >> - drm_atomic_helper_commit_modeset_enables(dev, old_state);
> >> drm_atomic_helper_commit_planes(dev, old_state,
> >> DRM_PLANE_COMMIT_ACTIVE_ONLY);
> >
> > Except for DRM_PLANE_COMMIT_ACTIVE_ONLY, this function now looks very much
> > like the default drm_atomic_helper_commit_tail() code.
> >
> > Reading around other uses /variants of commit_tail() style functions in
> > other drivers has left me confused as to how the ordering affects things
> > here.
> >
> > Could be worth adding a comment at least to describe why we can't use the
> > default helper...
>
> Or better still ... Use Maxime's new :
>
> [PATCH 1/4] drm/atomic: implement drm_atomic_helper_commit_tail for
> runtime_pm users
Note that Maxime's patch implements the commit tail as
drm_atomic_helper_commit_modeset_disables(dev, old_state);
drm_atomic_helper_commit_modeset_enables(dev, old_state);
drm_atomic_helper_commit_planes(dev, old_state,
DRM_PLANE_COMMIT_ACTIVE_ONLY);
while this patches moves the drm_atomic_helper_commit_planes() back between
drm_atomic_helper_commit_modeset_disables() and
drm_atomic_helper_commit_modeset_enables().
> >> + drm_atomic_helper_commit_modeset_enables(dev, old_state);
> >>
> >> drm_atomic_helper_commit_hw_done(old_state);
> >> drm_atomic_helper_wait_for_vblanks(dev, old_state);
--
Regards,
Laurent Pinchart
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