[PATCH] drm: add a drm_atomic_helper_plane_check_update

[John Hunter]

So we should remove the can_update_disabled parameter, and set it to true
in the drm_plane_helper_check_update callback?

I am still learning the atomic world, pls forgive if I don't understand it
well

On Mon, Jul 13, 2015 at 3:17 PM, Maarten Lankhorst <
maarten.lankhorst at linux.intel.com> wrote:

> Op 13-07-15 om 09:12 schreef Maarten Lankhorst:
> > Op 13-07-15 om 02:21 schreef John Hunter:
> >> From: Zhao Junwang <zhjwpku at gmail.com>
> >>
> >> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> >> Signed-off-by: Zhao Junwang <zhjwpku at gmail.com>
> >> ---
> >>  drivers/gpu/drm/drm_atomic_helper.c |   55
> +++++++++++++++++++++++++++++++++++
> >>  include/drm/drm_atomic_helper.h     |    7 +++++
> >>  2 files changed, 62 insertions(+)
> >>
> >> diff --git a/drivers/gpu/drm/drm_atomic_helper.c
> b/drivers/gpu/drm/drm_atomic_helper.c
> >> index 536ae4d..3d94ff8 100644
> >> --- a/drivers/gpu/drm/drm_atomic_helper.c
> >> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> >> @@ -1336,6 +1336,61 @@ void drm_atomic_helper_swap_state(struct
> drm_device *dev,
> >>  EXPORT_SYMBOL(drm_atomic_helper_swap_state);
> >>
> >>  /**
> >> + * drm_atomic_helper_plane_check_update
> >> + * @plane: plane object to update
> > == plane_state->plane, so can be removed
> >> + * @state: drm plane state
> > rename to plane_state
> >> + * @min_scale: minimum @src:@dest scaling factor in 16.16 fixed point
> >> + * @max_scale: maximum @src:@dest scaling factor in 16.16 fixed point
> >> + * @can_position: is it legal to position the plane such that it
> >> + *                doesn't cover the entire crtc?  This will generally
> >> + *                only be false for primary planes.
> >> + * @can_update_disabled: can the plane be updated while the crtc
> >> + *                       is disabled?
> >> + *
> > If you look carefully at drm_plane_helper_check_update,
> can_update_disabled will be a noop,
> > so remove this parameter.
> >
> > plane_state->crtc != NULL iff plane_state->fb != NULL
> >
> Oops, should check harder before I hit send. You can disable a crtc with
> planes attached, but the clip
> will be bogus in that case. When !crtc->enable the clip will be set { 0,
> 0, 0, 0 }, hiding the plane.
>
> There's still no need for can_update_disabled in the atomic world though,
> the plane state will be properly recalculated during a modeset.
> If you don't want to update a plane while a crtc is disabled, just don't
> update it in your commit function.
>



-- 
Best regards
Junwang Zhao
Microprocessor Research and Develop Center
Department of Computer Science &Technology
Peking University
Beijing, 100871, PRC
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