On Mon, Sep 23, 2019 at 10:10:26AM +0000, Mihail Atanassov wrote: > When initially turning a crtc on, drm_reset_vblank_timestamp will > set the vblank timestamp to 0 for any driver that doesn't provide > a ->get_vblank_timestamp() hook. > > Unfortunately, the FLIP_COMPLETE event depends on that timestamp, > and the only way to regenerate a valid one is to have vblank > interrupts enabled and have a valid in-ISR call to > drm_crtc_handle_vblank. > > Additionally, if the user doesn't request vblanks but _does_ request > FLIP_COMPLETE events, we still don't have a good timestamp: it'll be the > same stamp as the last vblank one. > > Work around the issue by always enabling vblanks when the CRTC is on. > Reducing the amount of time that PL0 has to be unmasked would be nice to > fix at a later time. > > Changes since v1 [https://patchwork.freedesktop.org/patch/331727/]: > - moved drm_crtc_vblank_put call to the ->atomic_disable() hook > > Cc: Daniel Vetter <daniel@xxxxxxxx> > Cc: Liviu Dudau <Liviu.Dudau@xxxxxxx> > Signed-off-by: Mihail Atanassov <mihail.atanassov@xxxxxxx> > --- > drivers/gpu/drm/arm/display/komeda/komeda_crtc.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c b/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c > index 34bc73ca18bc..d06679afb228 100644 > --- a/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c > +++ b/drivers/gpu/drm/arm/display/komeda/komeda_crtc.c > @@ -489,6 +489,7 @@ komeda_crtc_atomic_enable(struct drm_crtc *crtc, > pm_runtime_get_sync(crtc->dev->dev); > komeda_crtc_prepare(to_kcrtc(crtc)); > drm_crtc_vblank_on(crtc); > + WARN_ON(drm_crtc_vblank_get(crtc)); > komeda_crtc_do_flush(crtc, old); > } > > @@ -581,6 +582,7 @@ komeda_crtc_atomic_disable(struct drm_crtc *crtc, > komeda_crtc_flush_and_wait_for_flip_done(kcrtc, disable_done); > } > > + drm_crtc_vblank_put(crtc); > drm_crtc_vblank_off(crtc); > komeda_crtc_unprepare(kcrtc); > pm_runtime_put(crtc->dev->dev); Looks good to me. Reviewed-by: James Qian Wang (Arm Technology China) <james.qian.wang@xxxxxxx> _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
