On 11/16/15 18:06, Daniel Vetter wrote:
On Thu, Nov 05, 2015 at 05:03:09PM +0200, Jyri Sarha wrote:
Disable planes if they are on to be blanked CRTC and enable them when
the CRTC is turned back on by DMPS.
This is desirable on HW that loses its context on blanking. When
planes are enabled and disabled with the associated CRTCs, there is no
need to restore the plane context in runtime_resume callback.
Signed-off-by: Jyri Sarha <jsarha@xxxxxx>
---
We would need something like this to get rid off OMAPDSS somewhat
messy runtime_resume code. How does this look, could this generic
solution be refined to be acceptable to mainline, or should we start
looking a local solution to omapdrm?
BTW, with this patch the planes are sometimes disabled multiple
times. So probably a boolean (or maybe two like on crtc) should be
added to drm_plane_state to track and avoid multiple shutdowns.
The recommended way to do this is to call drm_atomic_add_affected_planes
from your crtc's atomic_check callback when active_changed is set. This
will also take care of enabling all planes again. For disabling we don't
yet have a helper yet, but it would be easy to create a
drm_atomic_helper_disable_planes(crtc) which just walks over all planes in
an atomic update that are currently using the given crtc and disables it
using plane_helper_funcs->atomic_disable. That would again require
drm_atomic_add_affected_planes to be called first.
This way current helper behaviour is unchanged, but it'd be easy to
construct the behaviour you want using helpers with
drm_atomic_add_affected_planes called from the crtc->disable hook.
I thought there was an rfc patch somewhere for this, but I can't find it
any more.
It appears that in the end these instructions were really all I needed.
There is only one thing that still bothers me. When implementing the
feature you described above, I had a print in the code to see if it
actually did anything. At first - because of my mistake - it did not,
but the plane context was still restored just fine on drm_next and
mainline linux. However the same omapdrm code did not restore the plane
context on our 4.1 based Linux branch.
So something similar to what I tried to accomplish has been implemented
some where between Linux 4.1 and 4.3?
Anyway, after back-porting the above fix works perfectly on our 4.1
based branch.
Thanks,
Jyri
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