Re: [PATCH] drm: add a drm_atomic_helper_plane_check_update

[Maarten Lankhorst <maarten.lankhorst@linux.intel.com>]

Op 13-07-15 om 09:12 schreef Maarten Lankhorst:
> Op 13-07-15 om 02:21 schreef John Hunter:
>> From: Zhao Junwang <zhjwpku@gmail.com>
>>
>> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
>> Signed-off-by: Zhao Junwang <zhjwpku@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.
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