| Message ID | 20200120122051.25178-2-tzimmermann@suse.de (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Use no_vblank property for drivers without VBLANK | expand |
On Mon, Jan 20, 2020 at 01:20:48PM +0100, Thomas Zimmermann wrote: > The new interface drm_crtc_has_vblank() return true if vblanking has > been initialized for a certain CRTC, or false otherwise. This function > will be useful for initializing CRTC state. > > Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> > --- > drivers/gpu/drm/drm_vblank.c | 21 +++++++++++++++++++++ > include/drm/drm_vblank.h | 1 + > 2 files changed, 22 insertions(+) > > diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c > index 1659b13b178c..c20102899411 100644 > --- a/drivers/gpu/drm/drm_vblank.c > +++ b/drivers/gpu/drm/drm_vblank.c > @@ -501,6 +501,27 @@ int drm_vblank_init(struct drm_device *dev, unsigned int num_crtcs) > } > EXPORT_SYMBOL(drm_vblank_init); > > +/** > + * drm_crtc_has_vblank - test if vblanking has been initialized for > + * a CRTC > + * @crtc: the CRTC > + * > + * Drivers may call this function to test if vblank support is > + * initialized for a CRTC. For most hardware this means that vblanking > + * can also be enabled on the CRTC. > + * > + * Returns: > + * True if vblanking has been initialized for the given CRTC, false > + * otherwise. > + */ > +bool drm_crtc_has_vblank(const struct drm_crtc *crtc) So making this specific to a CRTC sounds like a good idea. But it's not the reality, drm_vblank.c assumes that either everything or nothing supports vblanks. The reason for dev->num_crtcs is historical baggage, it predates kms by a few years. For kms drivers the only two valid values are either 0 or dev->mode_config.num_crtcs. Yes that's an entire different can of worms that's been irking me since forever (ideally drm_vblank_init would somehow loose the num_crtcs argument for kms drivers, but some drivers call this before they've done all the drm_crtc_init calls so it's complicated). Hence drm_dev_has_vblank as I suggested. That would also allow you to replace a bunch of if (dev->num_crtcs) checks in drm_vblank.c, which should help quite a bit in code readability. Cheers, Daniel > +{ > + struct drm_device *dev = crtc->dev; > + > + return crtc->index < dev->num_crtcs; > +} > +EXPORT_SYMBOL(drm_crtc_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_vblank.h b/include/drm/drm_vblank.h > index c16c44052b3d..531a6bc12b7e 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_crtc_has_vblank(const struct drm_crtc *crtc); > u64 drm_crtc_vblank_count(struct drm_crtc *crtc); > u64 drm_crtc_vblank_count_and_time(struct drm_crtc *crtc, > ktime_t *vblanktime); > -- > 2.24.1 >
Hi Am 22.01.20 um 09:31 schrieb Daniel Vetter: > On Mon, Jan 20, 2020 at 01:20:48PM +0100, Thomas Zimmermann wrote: >> The new interface drm_crtc_has_vblank() return true if vblanking has >> been initialized for a certain CRTC, or false otherwise. This function >> will be useful for initializing CRTC state. >> >> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> >> --- >> drivers/gpu/drm/drm_vblank.c | 21 +++++++++++++++++++++ >> include/drm/drm_vblank.h | 1 + >> 2 files changed, 22 insertions(+) >> >> diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c >> index 1659b13b178c..c20102899411 100644 >> --- a/drivers/gpu/drm/drm_vblank.c >> +++ b/drivers/gpu/drm/drm_vblank.c >> @@ -501,6 +501,27 @@ int drm_vblank_init(struct drm_device *dev, unsigned int num_crtcs) >> } >> EXPORT_SYMBOL(drm_vblank_init); >> >> +/** >> + * drm_crtc_has_vblank - test if vblanking has been initialized for >> + * a CRTC >> + * @crtc: the CRTC >> + * >> + * Drivers may call this function to test if vblank support is >> + * initialized for a CRTC. For most hardware this means that vblanking >> + * can also be enabled on the CRTC. >> + * >> + * Returns: >> + * True if vblanking has been initialized for the given CRTC, false >> + * otherwise. >> + */ >> +bool drm_crtc_has_vblank(const struct drm_crtc *crtc) > > So making this specific to a CRTC sounds like a good idea. But it's not > the reality, drm_vblank.c assumes that either everything or nothing > supports vblanks. > > The reason for dev->num_crtcs is historical baggage, it predates kms by a > few years. For kms drivers the only two valid values are either 0 or > dev->mode_config.num_crtcs. Yes that's an entire different can of worms > that's been irking me since forever (ideally drm_vblank_init would somehow > loose the num_crtcs argument for kms drivers, but some drivers call this > before they've done all the drm_crtc_init calls so it's complicated). Maybe as a first step, drm_vblank_init() could use dev->mode_config.num_crtcs if the supplied number of CRTCs is zero. > > Hence drm_dev_has_vblank as I suggested. That would also allow you to > replace a bunch of if (dev->num_crtcs) checks in drm_vblank.c, which > should help quite a bit in code readability. OK, but I still don't understand why this interface is better overall. We don't loose anything by passing in the crtc instead of the device structure. And if there's ever a per-crtc vblank initialization, we'd have the interface in place already. The tests with "if (dev->num_crtcs)" could probably be removed in most places in any case. We should also consider forking the vblank code for non-KMS drivers. While working in this, I found the support for legacy drivers is getting in the way at times. With such a fork, legacy drivers could continue using struct drm_vblank_crtc, while modern drivers could maybe store vblank state directly in struct drm_crtc. Anyway, all this is for another patch. Unless you change your mind, I'll replace drm_crtc_has_vblank() with drm_dev_has_vblank() for the patchset's next iteration. Best regards Thomas > > Cheers, Daniel > >> +{ >> + struct drm_device *dev = crtc->dev; >> + >> + return crtc->index < dev->num_crtcs; >> +} >> +EXPORT_SYMBOL(drm_crtc_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_vblank.h b/include/drm/drm_vblank.h >> index c16c44052b3d..531a6bc12b7e 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_crtc_has_vblank(const struct drm_crtc *crtc); >> u64 drm_crtc_vblank_count(struct drm_crtc *crtc); >> u64 drm_crtc_vblank_count_and_time(struct drm_crtc *crtc, >> ktime_t *vblanktime); >> -- >> 2.24.1 >> >
On Wed, Jan 22, 2020 at 09:53:42AM +0100, Thomas Zimmermann wrote: > Hi > > Am 22.01.20 um 09:31 schrieb Daniel Vetter: > > On Mon, Jan 20, 2020 at 01:20:48PM +0100, Thomas Zimmermann wrote: > >> The new interface drm_crtc_has_vblank() return true if vblanking has > >> been initialized for a certain CRTC, or false otherwise. This function > >> will be useful for initializing CRTC state. > >> > >> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> > >> --- > >> drivers/gpu/drm/drm_vblank.c | 21 +++++++++++++++++++++ > >> include/drm/drm_vblank.h | 1 + > >> 2 files changed, 22 insertions(+) > >> > >> diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c > >> index 1659b13b178c..c20102899411 100644 > >> --- a/drivers/gpu/drm/drm_vblank.c > >> +++ b/drivers/gpu/drm/drm_vblank.c > >> @@ -501,6 +501,27 @@ int drm_vblank_init(struct drm_device *dev, unsigned int num_crtcs) > >> } > >> EXPORT_SYMBOL(drm_vblank_init); > >> > >> +/** > >> + * drm_crtc_has_vblank - test if vblanking has been initialized for > >> + * a CRTC > >> + * @crtc: the CRTC > >> + * > >> + * Drivers may call this function to test if vblank support is > >> + * initialized for a CRTC. For most hardware this means that vblanking > >> + * can also be enabled on the CRTC. > >> + * > >> + * Returns: > >> + * True if vblanking has been initialized for the given CRTC, false > >> + * otherwise. > >> + */ > >> +bool drm_crtc_has_vblank(const struct drm_crtc *crtc) > > > > So making this specific to a CRTC sounds like a good idea. But it's not > > the reality, drm_vblank.c assumes that either everything or nothing > > supports vblanks. > > > > The reason for dev->num_crtcs is historical baggage, it predates kms by a > > few years. For kms drivers the only two valid values are either 0 or > > dev->mode_config.num_crtcs. Yes that's an entire different can of worms > > that's been irking me since forever (ideally drm_vblank_init would somehow > > loose the num_crtcs argument for kms drivers, but some drivers call this > > before they've done all the drm_crtc_init calls so it's complicated). > > Maybe as a first step, drm_vblank_init() could use > dev->mode_config.num_crtcs if the supplied number of CRTCs is zero. > > > > > Hence drm_dev_has_vblank as I suggested. That would also allow you to > > replace a bunch of if (dev->num_crtcs) checks in drm_vblank.c, which > > should help quite a bit in code readability. > > OK, but I still don't understand why this interface is better overall. > We don't loose anything by passing in the crtc instead of the device > structure. And if there's ever a per-crtc vblank initialization, we'd > have the interface in place already. The tests with "if > (dev->num_crtcs)" could probably be removed in most places in any case. You can't use it in drm_vblank.c code, because we only have the drm_device, not the drm_crtc (in most places at least). Your other patch series to deprecate the drm_device callbacks for vblanks is a huge step into the direction to fix that, but still more work needed: We'd essentially need to copypaste drm_vblank.c into drm_crtc_vblank.c for kms drivers, and in that copy switch from (dev, pipe) to crtc everywhere. Plus then move the drm_vblank structure into struct drm_crtc. Wrt removing the check: In a pile of cases it changes the return value, which matters both for vblank usage in helper code and the ioctl itself. From a quick look most of the checks that don't matter are already wrapped in a WARN. > We should also consider forking the vblank code for non-KMS drivers. > While working in this, I found the support for legacy drivers is getting > in the way at times. With such a fork, legacy drivers could continue > using struct drm_vblank_crtc, while modern drivers could maybe store > vblank state directly in struct drm_crtc. Hm if you want to do all that then the drm_crtc_has_vblank makes sense. But only after we've done the full split. So maybe make the public function drm_crtc_has_vblank, which calls the internal-only drm_has_vblank, and use that internally in drm_vblank.c? btw I still think a sub-struct for vblank stuff in drm_crtc makes sense, and drm_vblank_crtc seems to mostly fit the bill. That way we're at least not adding the the conversion pain of switching the vblank code over to drm_crtc fully. Thoughts? -Daniel > Anyway, all this is for another patch. Unless you change your mind, I'll > replace drm_crtc_has_vblank() with drm_dev_has_vblank() for the > patchset's next iteration. > > Best regards > Thomas > > > > > Cheers, Daniel > > > >> +{ > >> + struct drm_device *dev = crtc->dev; > >> + > >> + return crtc->index < dev->num_crtcs; > >> +} > >> +EXPORT_SYMBOL(drm_crtc_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_vblank.h b/include/drm/drm_vblank.h > >> index c16c44052b3d..531a6bc12b7e 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_crtc_has_vblank(const struct drm_crtc *crtc); > >> u64 drm_crtc_vblank_count(struct drm_crtc *crtc); > >> u64 drm_crtc_vblank_count_and_time(struct drm_crtc *crtc, > >> ktime_t *vblanktime); > >> -- > >> 2.24.1 > >> > > > > -- > Thomas Zimmermann > Graphics Driver Developer > SUSE Software Solutions Germany GmbH > Maxfeldstr. 5, 90409 Nürnberg, Germany > (HRB 36809, AG Nürnberg) > Geschäftsführer: Felix Imendörffer >
Hi Am 22.01.20 um 10:04 schrieb Daniel Vetter: > On Wed, Jan 22, 2020 at 09:53:42AM +0100, Thomas Zimmermann wrote: >> Hi >> >> Am 22.01.20 um 09:31 schrieb Daniel Vetter: >>> On Mon, Jan 20, 2020 at 01:20:48PM +0100, Thomas Zimmermann wrote: >>>> The new interface drm_crtc_has_vblank() return true if vblanking has >>>> been initialized for a certain CRTC, or false otherwise. This function >>>> will be useful for initializing CRTC state. >>>> >>>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> >>>> --- >>>> drivers/gpu/drm/drm_vblank.c | 21 +++++++++++++++++++++ >>>> include/drm/drm_vblank.h | 1 + >>>> 2 files changed, 22 insertions(+) >>>> >>>> diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c >>>> index 1659b13b178c..c20102899411 100644 >>>> --- a/drivers/gpu/drm/drm_vblank.c >>>> +++ b/drivers/gpu/drm/drm_vblank.c >>>> @@ -501,6 +501,27 @@ int drm_vblank_init(struct drm_device *dev, unsigned int num_crtcs) >>>> } >>>> EXPORT_SYMBOL(drm_vblank_init); >>>> >>>> +/** >>>> + * drm_crtc_has_vblank - test if vblanking has been initialized for >>>> + * a CRTC >>>> + * @crtc: the CRTC >>>> + * >>>> + * Drivers may call this function to test if vblank support is >>>> + * initialized for a CRTC. For most hardware this means that vblanking >>>> + * can also be enabled on the CRTC. >>>> + * >>>> + * Returns: >>>> + * True if vblanking has been initialized for the given CRTC, false >>>> + * otherwise. >>>> + */ >>>> +bool drm_crtc_has_vblank(const struct drm_crtc *crtc) >>> >>> So making this specific to a CRTC sounds like a good idea. But it's not >>> the reality, drm_vblank.c assumes that either everything or nothing >>> supports vblanks. >>> >>> The reason for dev->num_crtcs is historical baggage, it predates kms by a >>> few years. For kms drivers the only two valid values are either 0 or >>> dev->mode_config.num_crtcs. Yes that's an entire different can of worms >>> that's been irking me since forever (ideally drm_vblank_init would somehow >>> loose the num_crtcs argument for kms drivers, but some drivers call this >>> before they've done all the drm_crtc_init calls so it's complicated). >> >> Maybe as a first step, drm_vblank_init() could use >> dev->mode_config.num_crtcs if the supplied number of CRTCs is zero. >> >>> >>> Hence drm_dev_has_vblank as I suggested. That would also allow you to >>> replace a bunch of if (dev->num_crtcs) checks in drm_vblank.c, which >>> should help quite a bit in code readability. >> >> OK, but I still don't understand why this interface is better overall. >> We don't loose anything by passing in the crtc instead of the device >> structure. And if there's ever a per-crtc vblank initialization, we'd >> have the interface in place already. The tests with "if >> (dev->num_crtcs)" could probably be removed in most places in any case. > > You can't use it in drm_vblank.c code, because we only have the > drm_device, not the drm_crtc (in most places at least). Your other patch > series to deprecate the drm_device callbacks for vblanks is a huge step > into the direction to fix that, but still more work needed: We'd > essentially need to copypaste drm_vblank.c into drm_crtc_vblank.c for kms > drivers, and in that copy switch from (dev, pipe) to crtc everywhere. Plus > then move the drm_vblank structure into struct drm_crtc. > > Wrt removing the check: In a pile of cases it changes the return value, > which matters both for vblank usage in helper code and the ioctl itself. > From a quick look most of the checks that don't matter are already wrapped > in a WARN. > >> We should also consider forking the vblank code for non-KMS drivers. >> While working in this, I found the support for legacy drivers is getting >> in the way at times. With such a fork, legacy drivers could continue >> using struct drm_vblank_crtc, while modern drivers could maybe store >> vblank state directly in struct drm_crtc. > > Hm if you want to do all that then the drm_crtc_has_vblank makes sense. > But only after we've done the full split. So maybe make the public > function drm_crtc_has_vblank, which calls the internal-only > drm_has_vblank, and use that internally in drm_vblank.c? > > btw I still think a sub-struct for vblank stuff in drm_crtc makes sense, > and drm_vblank_crtc seems to mostly fit the bill. > > That way we're at least not adding the the conversion pain of switching > the vblank code over to drm_crtc fully. > > Thoughts? That all sounds good. Using struct drm_vblank_crtc with legacy and modern vblank functions, might allow us to continue to share some of the implementation. Wrt the current interface, drm_dev_has_vblank() is only called in a single place, so switching to drm_crtc_has_vblank() later would not be hard. Best regards Thomas > -Daniel > >> Anyway, all this is for another patch. Unless you change your mind, I'll >> replace drm_crtc_has_vblank() with drm_dev_has_vblank() for the >> patchset's next iteration. >> >> Best regards >> Thomas >> >>> >>> Cheers, Daniel >>> >>>> +{ >>>> + struct drm_device *dev = crtc->dev; >>>> + >>>> + return crtc->index < dev->num_crtcs; >>>> +} >>>> +EXPORT_SYMBOL(drm_crtc_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_vblank.h b/include/drm/drm_vblank.h >>>> index c16c44052b3d..531a6bc12b7e 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_crtc_has_vblank(const struct drm_crtc *crtc); >>>> u64 drm_crtc_vblank_count(struct drm_crtc *crtc); >>>> u64 drm_crtc_vblank_count_and_time(struct drm_crtc *crtc, >>>> ktime_t *vblanktime); >>>> -- >>>> 2.24.1 >>>> >>> >> >> -- >> 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_vblank.c b/drivers/gpu/drm/drm_vblank.c index 1659b13b178c..c20102899411 100644 --- a/drivers/gpu/drm/drm_vblank.c +++ b/drivers/gpu/drm/drm_vblank.c @@ -501,6 +501,27 @@ int drm_vblank_init(struct drm_device *dev, unsigned int num_crtcs) } EXPORT_SYMBOL(drm_vblank_init); +/** + * drm_crtc_has_vblank - test if vblanking has been initialized for + * a CRTC + * @crtc: the CRTC + * + * Drivers may call this function to test if vblank support is + * initialized for a CRTC. For most hardware this means that vblanking + * can also be enabled on the CRTC. + * + * Returns: + * True if vblanking has been initialized for the given CRTC, false + * otherwise. + */ +bool drm_crtc_has_vblank(const struct drm_crtc *crtc) +{ + struct drm_device *dev = crtc->dev; + + return crtc->index < dev->num_crtcs; +} +EXPORT_SYMBOL(drm_crtc_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_vblank.h b/include/drm/drm_vblank.h index c16c44052b3d..531a6bc12b7e 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_crtc_has_vblank(const struct drm_crtc *crtc); u64 drm_crtc_vblank_count(struct drm_crtc *crtc); u64 drm_crtc_vblank_count_and_time(struct drm_crtc *crtc, ktime_t *vblanktime);
The new interface drm_crtc_has_vblank() return true if vblanking has been initialized for a certain CRTC, or false otherwise. This function will be useful for initializing CRTC state. Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> --- drivers/gpu/drm/drm_vblank.c | 21 +++++++++++++++++++++ include/drm/drm_vblank.h | 1 + 2 files changed, 22 insertions(+)