| Message ID | 20200123092123.28368-2-tzimmermann@suse.de (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Use no_vblank property for drivers without VBLANK | expand |
On Thu, Jan 23, 2020 at 10:21:09AM +0100, Thomas Zimmermann wrote: > At the end of a commit, atomic helpers can generate a VBLANK event > automatically. Originally implemented for writeback connectors, the > functionality can be used by any driver and/or hardware without proper > VBLANK interrupt. > > The patch updates the documentation to make this behaviour official: > settings struct drm_crtc_state.no_vblank to true enables automatic > VBLANK generation. > > The new interface drm_dev_has_vblank() returns true if vblanking has > been initialized for a device, or false otherwise. This function will > be useful when initializing no_vblank in the CRTC state. > > Atomic modesetting helper set the initial value of no_vblank in > drm_atomic_helper_check_modeset(). If vblanking has been initialized > for a device, no_blank is disabled. Otherwise it's enabled. Hence, > atomic helpers will automatically send out VBLANK events with any > driver that did not initialize vblanking. > > v4: > * replace drm_crtc_has_vblank() with drm_dev_has_vblank() > * add drm_dev_crtc_has_vblank() in this patch drm_dev_has_vblank I guess? > * move driver changes into separate patches > v3: > * squash all related changes patches into this patch > > Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> > Acked-by: Gerd Hoffmann <kraxel@redhat.com> > --- > drivers/gpu/drm/drm_atomic_helper.c | 10 +++++++++- > drivers/gpu/drm/drm_vblank.c | 28 ++++++++++++++++++++++++++++ > include/drm/drm_crtc.h | 27 ++++++++++++++++++++------- > include/drm/drm_simple_kms_helper.h | 7 +++++-- > include/drm/drm_vblank.h | 1 + > 5 files changed, 63 insertions(+), 10 deletions(-) > > diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c > index 4511c2e07bb9..d7b73cd89b79 100644 > --- a/drivers/gpu/drm/drm_atomic_helper.c > +++ b/drivers/gpu/drm/drm_atomic_helper.c > @@ -583,6 +583,7 @@ mode_valid(struct drm_atomic_state *state) > * &drm_crtc_state.connectors_changed is set when a connector is added or > * removed from the CRTC. &drm_crtc_state.active_changed is set when > * &drm_crtc_state.active changes, which is used for DPMS. > + * &drm_crtc_state.no_vblank is set from the result of drm_dev_has_vblank(). > * See also: drm_atomic_crtc_needs_modeset() > * > * IMPORTANT: > @@ -649,6 +650,11 @@ drm_atomic_helper_check_modeset(struct drm_device *dev, > > return -EINVAL; > } > + > + if (drm_dev_has_vblank(dev)) > + new_crtc_state->no_vblank = false; > + else > + new_crtc_state->no_vblank = true; > } > > ret = handle_conflicting_encoders(state, false); > @@ -2215,7 +2221,9 @@ EXPORT_SYMBOL(drm_atomic_helper_wait_for_dependencies); > * when a job is queued, and any change to the pipeline that does not touch the > * connector is leading to timeouts when calling > * drm_atomic_helper_wait_for_vblanks() or > - * drm_atomic_helper_wait_for_flip_done(). > + * drm_atomic_helper_wait_for_flip_done(). In addition to writeback > + * connectors, this function can also fake VBLANK events for CRTCs without > + * VBLANK interrupt. > * > * This is part of the atomic helper support for nonblocking commits, see > * drm_atomic_helper_setup_commit() for an overview. > diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c > index 1659b13b178c..433dec6230b1 100644 > --- a/drivers/gpu/drm/drm_vblank.c > +++ b/drivers/gpu/drm/drm_vblank.c > @@ -69,6 +69,12 @@ > * &drm_driver.max_vblank_count. In that case the vblank core only disables the > * vblanks after a timer has expired, which can be configured through the > * ``vblankoffdelay`` module parameter. > + * > + * Drivers for hardware without support for vertical-blanking interrupts > + * must not call drm_vblank_init(). For such drivers, atomic helpers will > + * automatically generate vblank events as part of the display update. This > + * functionality also can be controlled by the driver by enabling and disabling > + * struct drm_crtc_state.no_vblank. > */ > > /* Retry timestamp calculation up to 3 times to satisfy > @@ -501,6 +507,28 @@ int drm_vblank_init(struct drm_device *dev, unsigned int num_crtcs) > } > EXPORT_SYMBOL(drm_vblank_init); > > +/** > + * drm_dev_has_vblank - test if vblanking has been initialized for > + * a device > + * @dev: the device > + * > + * Drivers may call this function to test if vblank support is > + * initialized for a device. For most hardware this means that vblanking > + * can also be enabled. > + * > + * Atomic helpers use this function to initialize > + * &drm_crtc_state.no_vblank. See also drm_atomic_helper_check_modeset(). > + * > + * Returns: > + * True if vblanking has been initialized for the given device, false > + * otherwise. > + */ > +bool drm_dev_has_vblank(const struct drm_device *dev) > +{ > + return dev->num_crtcs != 0; > +} > +EXPORT_SYMBOL(drm_dev_has_vblank); > + > /** > * drm_crtc_vblank_waitqueue - get vblank waitqueue for the CRTC > * @crtc: which CRTC's vblank waitqueue to retrieve > diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h > index 5e9b15a0e8c5..5363e31c9abe 100644 > --- a/include/drm/drm_crtc.h > +++ b/include/drm/drm_crtc.h > @@ -174,12 +174,22 @@ struct drm_crtc_state { > * @no_vblank: > * > * Reflects the ability of a CRTC to send VBLANK events. This state > - * usually depends on the pipeline configuration, and the main usuage > - * is CRTCs feeding a writeback connector operating in oneshot mode. > - * In this case the VBLANK event is only generated when a job is queued > - * to the writeback connector, and we want the core to fake VBLANK > - * events when this part of the pipeline hasn't changed but others had > - * or when the CRTC and connectors are being disabled. > + * usually depends on the pipeline configuration. If set to true, DRM > + * atomic helpers will sendout a fake VBLANK event during display s/sendout/ send out/ > + * updates. maby add "... updates, after all hardware changes have been committed. This is implemented in drm_atomic_helper_fake_vblank()." That at least reflects the default behaviour. > + * > + * One usage is for drivers and/or hardware without support for VBLANK > + * interrupts. Such drivers typically do not initialize vblanking > + * (i.e., call drm_vblank_init() wit the number of CRTCs). For CRTCs s/wit/with/ > + * without initialized vblanking, the field is initialized to true and "initialized to true" is a bit a stretch, since this is done in the helpers. Maybe instead "... this field is set to true in drm_atomic_helper_check_modeset() and ..." > + * a VBLANK event will be send out on each update of the display > + * pipeline. Maybe also reiterate that this is done through drm_atomic_helper_fake_vblank() again? Imo for stuff done by helpers it's important to highligh where that's done, since it's all opt-in (even if most drivers will opt-in automatically). > + * > + * Another usage is CRTCs feeding a writeback connector operating in > + * oneshot mode. In this case the VBLANK event is only generated when > + * a job is queued to the writeback connector, and we want the core > + * to fake VBLANK events when this part of the pipeline hasn't changed > + * but others had or when the CRTC and connectors are being disabled. > * > * __drm_atomic_helper_crtc_duplicate_state() will not reset the value > * from the current state, the CRTC driver is then responsible for > @@ -335,7 +345,10 @@ struct drm_crtc_state { > * - Events for disabled CRTCs are not allowed, and drivers can ignore > * that case. > * > - * This can be handled by the drm_crtc_send_vblank_event() function, > + * For very simple hardware without VBLANK interrupt, enabling > + * &struct drm_crtc_state.no_vblank makes DRM's atomic commit helpers > + * send the event at an appropriate time. For more complex hardware this > + * can be handled by the drm_crtc_send_vblank_event() function, > * which the driver should call on the provided event upon completion of > * the atomic commit. Note that if the driver supports vblank signalling > * and timestamping the vblank counters and timestamps must agree with > diff --git a/include/drm/drm_simple_kms_helper.h b/include/drm/drm_simple_kms_helper.h > index 15afee9cf049..e253ba7bea9d 100644 > --- a/include/drm/drm_simple_kms_helper.h > +++ b/include/drm/drm_simple_kms_helper.h > @@ -100,8 +100,11 @@ struct drm_simple_display_pipe_funcs { > * This is the function drivers should submit the > * &drm_pending_vblank_event from. Using either > * drm_crtc_arm_vblank_event(), when the driver supports vblank > - * interrupt handling, or drm_crtc_send_vblank_event() directly in case > - * the hardware lacks vblank support entirely. > + * interrupt handling, or drm_crtc_send_vblank_event() for more > + * complex case. In case the hardware lacks vblank support entirely, > + * drivers can set &struct drm_crtc_state.no_vblank in > + * &struct drm_simple_display_pipe_funcs.check and let DRM's > + * atomic helper fake a vblank event. > */ > void (*update)(struct drm_simple_display_pipe *pipe, > struct drm_plane_state *old_plane_state); > diff --git a/include/drm/drm_vblank.h b/include/drm/drm_vblank.h > index c16c44052b3d..94275e93fd27 100644 > --- a/include/drm/drm_vblank.h > +++ b/include/drm/drm_vblank.h > @@ -206,6 +206,7 @@ struct drm_vblank_crtc { > }; > > int drm_vblank_init(struct drm_device *dev, unsigned int num_crtcs); > +bool drm_dev_has_vblank(const struct drm_device *dev); > u64 drm_crtc_vblank_count(struct drm_crtc *crtc); > u64 drm_crtc_vblank_count_and_time(struct drm_crtc *crtc, > ktime_t *vblanktime); With the doc nits addressed: Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> > -- > 2.24.1 >
Hi Thomas, On Thu, 23 Jan 2020 at 09:21, Thomas Zimmermann <tzimmermann@suse.de> wrote: > @@ -174,12 +174,22 @@ struct drm_crtc_state { > * @no_vblank: > * > * Reflects the ability of a CRTC to send VBLANK events. This state > - * usually depends on the pipeline configuration, and the main usuage > - * is CRTCs feeding a writeback connector operating in oneshot mode. > - * In this case the VBLANK event is only generated when a job is queued > - * to the writeback connector, and we want the core to fake VBLANK > - * events when this part of the pipeline hasn't changed but others had > - * or when the CRTC and connectors are being disabled. > + * usually depends on the pipeline configuration. If set to true, DRM > + * atomic helpers will sendout a fake VBLANK event during display > + * updates. > + * > + * One usage is for drivers and/or hardware without support for VBLANK > + * interrupts. Such drivers typically do not initialize vblanking > + * (i.e., call drm_vblank_init() wit the number of CRTCs). For CRTCs > + * without initialized vblanking, the field is initialized to true and > + * a VBLANK event will be send out on each update of the display > + * pipeline. > + * > + * Another usage is CRTCs feeding a writeback connector operating in > + * oneshot mode. In this case the VBLANK event is only generated when > + * a job is queued to the writeback connector, and we want the core > + * to fake VBLANK events when this part of the pipeline hasn't changed > + * but others had or when the CRTC and connectors are being disabled. > * Perhaps it's just me, yet the following ideas would make the topic significantly easier and clearer. - adding explicit "fake" when talking about drm/atomic _helpers_ generating/sending a VBLANK event. For example, in 15/15 the commit message says "fake", while inline comment omits it... Leading to the confusion pointed out. - s/no_vblank/fake_vblank/g or s/no_vblank/no_hw_vblank/g Simple and concise. With slight inclination towards the former wording :-) If you and Daniel agree with the rename, then the first sentence of the description should probably be tweaked. HTH Emil
Hi Emil Am 27.01.20 um 19:12 schrieb Emil Velikov: > Hi Thomas, > > On Thu, 23 Jan 2020 at 09:21, Thomas Zimmermann <tzimmermann@suse.de> wrote: > >> @@ -174,12 +174,22 @@ struct drm_crtc_state { >> * @no_vblank: >> * >> * Reflects the ability of a CRTC to send VBLANK events. This state >> - * usually depends on the pipeline configuration, and the main usuage >> - * is CRTCs feeding a writeback connector operating in oneshot mode. >> - * In this case the VBLANK event is only generated when a job is queued >> - * to the writeback connector, and we want the core to fake VBLANK >> - * events when this part of the pipeline hasn't changed but others had >> - * or when the CRTC and connectors are being disabled. >> + * usually depends on the pipeline configuration. If set to true, DRM >> + * atomic helpers will sendout a fake VBLANK event during display >> + * updates. >> + * >> + * One usage is for drivers and/or hardware without support for VBLANK >> + * interrupts. Such drivers typically do not initialize vblanking >> + * (i.e., call drm_vblank_init() wit the number of CRTCs). For CRTCs >> + * without initialized vblanking, the field is initialized to true and >> + * a VBLANK event will be send out on each update of the display >> + * pipeline. >> + * >> + * Another usage is CRTCs feeding a writeback connector operating in >> + * oneshot mode. In this case the VBLANK event is only generated when >> + * a job is queued to the writeback connector, and we want the core >> + * to fake VBLANK events when this part of the pipeline hasn't changed >> + * but others had or when the CRTC and connectors are being disabled. >> * > > Perhaps it's just me, yet the following ideas would make the topic > significantly easier and clearer. > > - adding explicit "fake" when talking about drm/atomic _helpers_ > generating/sending a VBLANK event. > For example, in 15/15 the commit message says "fake", while inline > comment omits it... Leading to the confusion pointed out. No problem on being more precise here. I'll update the docs accordingly. > > - s/no_vblank/fake_vblank/g or s/no_vblank/no_hw_vblank/g > Simple and concise. With slight inclination towards the former wording :-) I'd prefer to not change the field's name. The current name 'no_vblank' indicates state and lets helpers decide what to do with it. The name 'fake_vblank' indicates an instruction to the helpers, telling them what to do. It does neither seem to fit into drm_crtc_state, nor into the overall concept. Best regards Thomas > > If you and Daniel agree with the rename, then the first sentence of > the description should probably be tweaked. > > HTH > Emil >
On Mon, Jan 27, 2020 at 07:42:27PM +0100, Thomas Zimmermann wrote: > Hi Emil > > Am 27.01.20 um 19:12 schrieb Emil Velikov: > > Hi Thomas, > > > > On Thu, 23 Jan 2020 at 09:21, Thomas Zimmermann <tzimmermann@suse.de> wrote: > > > >> @@ -174,12 +174,22 @@ struct drm_crtc_state { > >> * @no_vblank: > >> * > >> * Reflects the ability of a CRTC to send VBLANK events. This state > >> - * usually depends on the pipeline configuration, and the main usuage > >> - * is CRTCs feeding a writeback connector operating in oneshot mode. > >> - * In this case the VBLANK event is only generated when a job is queued > >> - * to the writeback connector, and we want the core to fake VBLANK > >> - * events when this part of the pipeline hasn't changed but others had > >> - * or when the CRTC and connectors are being disabled. > >> + * usually depends on the pipeline configuration. If set to true, DRM > >> + * atomic helpers will sendout a fake VBLANK event during display > >> + * updates. > >> + * > >> + * One usage is for drivers and/or hardware without support for VBLANK > >> + * interrupts. Such drivers typically do not initialize vblanking > >> + * (i.e., call drm_vblank_init() wit the number of CRTCs). For CRTCs > >> + * without initialized vblanking, the field is initialized to true and > >> + * a VBLANK event will be send out on each update of the display > >> + * pipeline. > >> + * > >> + * Another usage is CRTCs feeding a writeback connector operating in > >> + * oneshot mode. In this case the VBLANK event is only generated when > >> + * a job is queued to the writeback connector, and we want the core > >> + * to fake VBLANK events when this part of the pipeline hasn't changed > >> + * but others had or when the CRTC and connectors are being disabled. > >> * > > > > Perhaps it's just me, yet the following ideas would make the topic > > significantly easier and clearer. > > > > - adding explicit "fake" when talking about drm/atomic _helpers_ > > generating/sending a VBLANK event. > > For example, in 15/15 the commit message says "fake", while inline > > comment omits it... Leading to the confusion pointed out. > > No problem on being more precise here. I'll update the docs accordingly. > > > > > - s/no_vblank/fake_vblank/g or s/no_vblank/no_hw_vblank/g > > Simple and concise. With slight inclination towards the former wording :-) > > I'd prefer to not change the field's name. The current name 'no_vblank' > indicates state and lets helpers decide what to do with it. The name > 'fake_vblank' indicates an instruction to the helpers, telling them what > to do. It does neither seem to fit into drm_crtc_state, nor into the > overall concept. Yeah e.g. xen has no hw vblank, but still has special processing of events, which are kinda triggered by the "hw" (it's an event from the compositor). Maybe the confusion is with the helper function that generates the fake_vblank, since it's not really a fake vblank at all, it's just "send out this atomic completion event now, I'm not going to do it as part of the vblank processing since no vblank". So maybe that function should be called _send_events_i_have_no_hw_vblank, which yeah is not a great name :-) But maybe you have an idea for that one? -Daniel > > Best regards > Thomas > > > > > If you and Daniel agree with the rename, then the first sentence of > > the description should probably be tweaked. > > > > HTH > > Emil > > > > -- > Thomas Zimmermann > Graphics Driver Developer > SUSE Software Solutions Germany GmbH > Maxfeldstr. 5, 90409 Nürnberg, Germany > (HRB 36809, AG Nürnberg) > Geschäftsführer: Felix Imendörffer >
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c index 4511c2e07bb9..d7b73cd89b79 100644 --- a/drivers/gpu/drm/drm_atomic_helper.c +++ b/drivers/gpu/drm/drm_atomic_helper.c @@ -583,6 +583,7 @@ mode_valid(struct drm_atomic_state *state) * &drm_crtc_state.connectors_changed is set when a connector is added or * removed from the CRTC. &drm_crtc_state.active_changed is set when * &drm_crtc_state.active changes, which is used for DPMS. + * &drm_crtc_state.no_vblank is set from the result of drm_dev_has_vblank(). * See also: drm_atomic_crtc_needs_modeset() * * IMPORTANT: @@ -649,6 +650,11 @@ drm_atomic_helper_check_modeset(struct drm_device *dev, return -EINVAL; } + + if (drm_dev_has_vblank(dev)) + new_crtc_state->no_vblank = false; + else + new_crtc_state->no_vblank = true; } ret = handle_conflicting_encoders(state, false); @@ -2215,7 +2221,9 @@ EXPORT_SYMBOL(drm_atomic_helper_wait_for_dependencies); * when a job is queued, and any change to the pipeline that does not touch the * connector is leading to timeouts when calling * drm_atomic_helper_wait_for_vblanks() or - * drm_atomic_helper_wait_for_flip_done(). + * drm_atomic_helper_wait_for_flip_done(). In addition to writeback + * connectors, this function can also fake VBLANK events for CRTCs without + * VBLANK interrupt. * * This is part of the atomic helper support for nonblocking commits, see * drm_atomic_helper_setup_commit() for an overview. diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c index 1659b13b178c..433dec6230b1 100644 --- a/drivers/gpu/drm/drm_vblank.c +++ b/drivers/gpu/drm/drm_vblank.c @@ -69,6 +69,12 @@ * &drm_driver.max_vblank_count. In that case the vblank core only disables the * vblanks after a timer has expired, which can be configured through the * ``vblankoffdelay`` module parameter. + * + * Drivers for hardware without support for vertical-blanking interrupts + * must not call drm_vblank_init(). For such drivers, atomic helpers will + * automatically generate vblank events as part of the display update. This + * functionality also can be controlled by the driver by enabling and disabling + * struct drm_crtc_state.no_vblank. */ /* Retry timestamp calculation up to 3 times to satisfy @@ -501,6 +507,28 @@ int drm_vblank_init(struct drm_device *dev, unsigned int num_crtcs) } EXPORT_SYMBOL(drm_vblank_init); +/** + * drm_dev_has_vblank - test if vblanking has been initialized for + * a device + * @dev: the device + * + * Drivers may call this function to test if vblank support is + * initialized for a device. For most hardware this means that vblanking + * can also be enabled. + * + * Atomic helpers use this function to initialize + * &drm_crtc_state.no_vblank. See also drm_atomic_helper_check_modeset(). + * + * Returns: + * True if vblanking has been initialized for the given device, false + * otherwise. + */ +bool drm_dev_has_vblank(const struct drm_device *dev) +{ + return dev->num_crtcs != 0; +} +EXPORT_SYMBOL(drm_dev_has_vblank); + /** * drm_crtc_vblank_waitqueue - get vblank waitqueue for the CRTC * @crtc: which CRTC's vblank waitqueue to retrieve diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h index 5e9b15a0e8c5..5363e31c9abe 100644 --- a/include/drm/drm_crtc.h +++ b/include/drm/drm_crtc.h @@ -174,12 +174,22 @@ struct drm_crtc_state { * @no_vblank: * * Reflects the ability of a CRTC to send VBLANK events. This state - * usually depends on the pipeline configuration, and the main usuage - * is CRTCs feeding a writeback connector operating in oneshot mode. - * In this case the VBLANK event is only generated when a job is queued - * to the writeback connector, and we want the core to fake VBLANK - * events when this part of the pipeline hasn't changed but others had - * or when the CRTC and connectors are being disabled. + * usually depends on the pipeline configuration. If set to true, DRM + * atomic helpers will sendout a fake VBLANK event during display + * updates. + * + * One usage is for drivers and/or hardware without support for VBLANK + * interrupts. Such drivers typically do not initialize vblanking + * (i.e., call drm_vblank_init() wit the number of CRTCs). For CRTCs + * without initialized vblanking, the field is initialized to true and + * a VBLANK event will be send out on each update of the display + * pipeline. + * + * Another usage is CRTCs feeding a writeback connector operating in + * oneshot mode. In this case the VBLANK event is only generated when + * a job is queued to the writeback connector, and we want the core + * to fake VBLANK events when this part of the pipeline hasn't changed + * but others had or when the CRTC and connectors are being disabled. * * __drm_atomic_helper_crtc_duplicate_state() will not reset the value * from the current state, the CRTC driver is then responsible for @@ -335,7 +345,10 @@ struct drm_crtc_state { * - Events for disabled CRTCs are not allowed, and drivers can ignore * that case. * - * This can be handled by the drm_crtc_send_vblank_event() function, + * For very simple hardware without VBLANK interrupt, enabling + * &struct drm_crtc_state.no_vblank makes DRM's atomic commit helpers + * send the event at an appropriate time. For more complex hardware this + * can be handled by the drm_crtc_send_vblank_event() function, * which the driver should call on the provided event upon completion of * the atomic commit. Note that if the driver supports vblank signalling * and timestamping the vblank counters and timestamps must agree with diff --git a/include/drm/drm_simple_kms_helper.h b/include/drm/drm_simple_kms_helper.h index 15afee9cf049..e253ba7bea9d 100644 --- a/include/drm/drm_simple_kms_helper.h +++ b/include/drm/drm_simple_kms_helper.h @@ -100,8 +100,11 @@ struct drm_simple_display_pipe_funcs { * This is the function drivers should submit the * &drm_pending_vblank_event from. Using either * drm_crtc_arm_vblank_event(), when the driver supports vblank - * interrupt handling, or drm_crtc_send_vblank_event() directly in case - * the hardware lacks vblank support entirely. + * interrupt handling, or drm_crtc_send_vblank_event() for more + * complex case. In case the hardware lacks vblank support entirely, + * drivers can set &struct drm_crtc_state.no_vblank in + * &struct drm_simple_display_pipe_funcs.check and let DRM's + * atomic helper fake a vblank event. */ void (*update)(struct drm_simple_display_pipe *pipe, struct drm_plane_state *old_plane_state); diff --git a/include/drm/drm_vblank.h b/include/drm/drm_vblank.h index c16c44052b3d..94275e93fd27 100644 --- a/include/drm/drm_vblank.h +++ b/include/drm/drm_vblank.h @@ -206,6 +206,7 @@ struct drm_vblank_crtc { }; int drm_vblank_init(struct drm_device *dev, unsigned int num_crtcs); +bool drm_dev_has_vblank(const struct drm_device *dev); u64 drm_crtc_vblank_count(struct drm_crtc *crtc); u64 drm_crtc_vblank_count_and_time(struct drm_crtc *crtc, ktime_t *vblanktime);