On 12/02/2020 16:33, Ville Syrjälä wrote: > On Wed, Feb 12, 2020 at 04:08:11PM +0200, Jyri Sarha wrote: >> 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@xxxxxx> >>> --- >>> 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(). > > You seem to be using drm_atomic_helper_check_planes(), which means > crtc.atomic_check() gets called after plane.atomic_check(). So this > might be good or bad depending on whether you'd like the planes you > add here to go through their .atomic_check() or not. > Should have thought of that my self. Extra plane.atomic_check() calls do not do any actual harm, but they are potentially expensive. The planes are really only needed there in the commit phase (crtc_enable() or flush()). Well, I'll do my own mode_config.atomic_check() and call drm_atomic_add_affected_planes() in a for_each_new_crtc_in_state()-loop after all the checks. Thanks, Jyri -- Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
