On 12/02/2020 15:59, Jyri Sarha wrote:
The old implementation of placing planes on the CRTC while configuring the planes was naive and relied on the order in which the planes were configured, enabled, and disabled. The situation where a plane's zpos was changed on the fly was completely broken. The usual symptoms of this problem was scrambled display and a flood of sync lost errors, when a plane was active in two layers at the same time, or a missing plane, in case when a layer was accidentally disabled.
The rewrite takes a more straight forward approach when HW is concerned. The plane positioning registers are in the CRTC (actually OVR) register space and it is more natural to configure them in one go while configuring the CRTC. To do this we need to make sure we have all the planes on updated CRTCs in the new atomic state to be committed. This is done by calling drm_atomic_add_affected_planes() in crtc_atomic_check().
Signed-off-by: Jyri Sarha jsarha@ti.com
drivers/gpu/drm/tidss/tidss_crtc.c | 55 ++++++++++++++++++++++++++++- drivers/gpu/drm/tidss/tidss_dispc.c | 55 +++++++++++------------------ drivers/gpu/drm/tidss/tidss_dispc.h | 5 +++ 3 files changed, 79 insertions(+), 36 deletions(-)
diff --git a/drivers/gpu/drm/tidss/tidss_crtc.c b/drivers/gpu/drm/tidss/tidss_crtc.c index 032c31ee2820..f7c5fd1094a8 100644 --- a/drivers/gpu/drm/tidss/tidss_crtc.c +++ b/drivers/gpu/drm/tidss/tidss_crtc.c
...
@@ -108,7 +110,54 @@ static int tidss_crtc_atomic_check(struct drm_crtc *crtc, return -EINVAL; }
- return dispc_vp_bus_check(dispc, hw_videoport, state);
- ret = dispc_vp_bus_check(dispc, hw_videoport, state);
- if (ret)
return ret;- /* Add unchanged planes on this crtc to state for zpos update. */
- return drm_atomic_add_affected_planes(state->state, crtc);
Is this a correct way to use drm_atomic_add_affected_planes()?
I saw that some other drivers implement their own mode_config atomic_check() and have this call there in for_each_new_crtc_in_state()-loop, but I thought it should be fine to call it in crtc_atomic_check().
BR, Jyri