| Message ID | 20190923101017.35114-1-mihail.atanassov@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] drm/komeda: Workaround for broken FLIP_COMPLETE timestamps | expand |
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@ffwll.ch> > Cc: Liviu Dudau <Liviu.Dudau@arm.com> > Signed-off-by: Mihail Atanassov <mihail.atanassov@arm.com> > --- > 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@arm.com>
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);
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@ffwll.ch> Cc: Liviu Dudau <Liviu.Dudau@arm.com> Signed-off-by: Mihail Atanassov <mihail.atanassov@arm.com> --- drivers/gpu/drm/arm/display/komeda/komeda_crtc.c | 2 ++ 1 file changed, 2 insertions(+)