| Message ID | 20210622141002.11590-5-tzimmermann@suse.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Deprecate struct drm_device.irq_enabled | expand |
Hello, On Tue, Jun 22, 2021 at 04:09:44PM +0200, Thomas Zimmermann wrote: > For KMS drivers, replace the IRQ check in VBLANK ioctls with a check for > vblank support. IRQs might be enabled wthout vblanking being supported. > > This change also removes the DRM framework's only dependency on IRQ state > for non-legacy drivers. For legacy drivers with userspace modesetting, > the original test remains in drm_wait_vblank_ioctl(). > > v2: > * keep the old test for legacy drivers in > drm_wait_vblank_ioctl() (Daniel) > > Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> > --- > drivers/gpu/drm/drm_irq.c | 10 +++------- > drivers/gpu/drm/drm_vblank.c | 13 +++++++++---- > 2 files changed, 12 insertions(+), 11 deletions(-) > > diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c > index c3bd664ea733..1d7785721323 100644 > --- a/drivers/gpu/drm/drm_irq.c > +++ b/drivers/gpu/drm/drm_irq.c > @@ -74,10 +74,8 @@ > * only supports devices with a single interrupt on the main device stored in > * &drm_device.dev and set as the device paramter in drm_dev_alloc(). > * > - * These IRQ helpers are strictly optional. Drivers which roll their own only > - * need to set &drm_device.irq_enabled to signal the DRM core that vblank > - * interrupts are working. Since these helpers don't automatically clean up the > - * requested interrupt like e.g. devm_request_irq() they're not really > + * These IRQ helpers are strictly optional. Since these helpers don't automatically > + * clean up the requested interrupt like e.g. devm_request_irq() they're not really > * recommended. > */ > > @@ -91,9 +89,7 @@ > * and after the installation. > * > * This is the simplified helper interface provided for drivers with no special > - * needs. Drivers which need to install interrupt handlers for multiple > - * interrupts must instead set &drm_device.irq_enabled to signal the DRM core > - * that vblank interrupts are available. > + * needs. > * > * @irq must match the interrupt number that would be passed to request_irq(), > * if called directly instead of using this helper function. > diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c > index 3417e1ac7918..a98a4aad5037 100644 > --- a/drivers/gpu/drm/drm_vblank.c > +++ b/drivers/gpu/drm/drm_vblank.c > @@ -1748,8 +1748,13 @@ int drm_wait_vblank_ioctl(struct drm_device *dev, void *data, > unsigned int pipe_index; > unsigned int flags, pipe, high_pipe; > > - if (!dev->irq_enabled) > - return -EOPNOTSUPP; > + if (drm_core_check_feature(dev, DRIVER_MODESET)) { > + if (!drm_dev_has_vblank(dev)) > + return -EOPNOTSUPP; > + } else { > + if (!dev->irq_enabled) > + return -EOPNOTSUPP; > + } For a system call that is used quite a lot by userspace we have increased the code size in a noticeable way. Can we not cache it privately? Best regards, Liviu > > if (vblwait->request.type & _DRM_VBLANK_SIGNAL) > return -EINVAL; > @@ -2023,7 +2028,7 @@ int drm_crtc_get_sequence_ioctl(struct drm_device *dev, void *data, > if (!drm_core_check_feature(dev, DRIVER_MODESET)) > return -EOPNOTSUPP; > > - if (!dev->irq_enabled) > + if (!drm_dev_has_vblank(dev)) > return -EOPNOTSUPP; > > crtc = drm_crtc_find(dev, file_priv, get_seq->crtc_id); > @@ -2082,7 +2087,7 @@ int drm_crtc_queue_sequence_ioctl(struct drm_device *dev, void *data, > if (!drm_core_check_feature(dev, DRIVER_MODESET)) > return -EOPNOTSUPP; > > - if (!dev->irq_enabled) > + if (!drm_dev_has_vblank(dev)) > return -EOPNOTSUPP; > > crtc = drm_crtc_find(dev, file_priv, queue_seq->crtc_id); > -- > 2.32.0 >
Hi Liviu Am 22.06.21 um 17:25 schrieb Liviu Dudau: > Hello, > > On Tue, Jun 22, 2021 at 04:09:44PM +0200, Thomas Zimmermann wrote: >> For KMS drivers, replace the IRQ check in VBLANK ioctls with a check for >> vblank support. IRQs might be enabled wthout vblanking being supported. >> >> This change also removes the DRM framework's only dependency on IRQ state >> for non-legacy drivers. For legacy drivers with userspace modesetting, >> the original test remains in drm_wait_vblank_ioctl(). >> >> v2: >> * keep the old test for legacy drivers in >> drm_wait_vblank_ioctl() (Daniel) >> >> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> >> --- >> drivers/gpu/drm/drm_irq.c | 10 +++------- >> drivers/gpu/drm/drm_vblank.c | 13 +++++++++---- >> 2 files changed, 12 insertions(+), 11 deletions(-) >> >> diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c >> index c3bd664ea733..1d7785721323 100644 >> --- a/drivers/gpu/drm/drm_irq.c >> +++ b/drivers/gpu/drm/drm_irq.c >> @@ -74,10 +74,8 @@ >> * only supports devices with a single interrupt on the main device stored in >> * &drm_device.dev and set as the device paramter in drm_dev_alloc(). >> * >> - * These IRQ helpers are strictly optional. Drivers which roll their own only >> - * need to set &drm_device.irq_enabled to signal the DRM core that vblank >> - * interrupts are working. Since these helpers don't automatically clean up the >> - * requested interrupt like e.g. devm_request_irq() they're not really >> + * These IRQ helpers are strictly optional. Since these helpers don't automatically >> + * clean up the requested interrupt like e.g. devm_request_irq() they're not really >> * recommended. >> */ >> >> @@ -91,9 +89,7 @@ >> * and after the installation. >> * >> * This is the simplified helper interface provided for drivers with no special >> - * needs. Drivers which need to install interrupt handlers for multiple >> - * interrupts must instead set &drm_device.irq_enabled to signal the DRM core >> - * that vblank interrupts are available. >> + * needs. >> * >> * @irq must match the interrupt number that would be passed to request_irq(), >> * if called directly instead of using this helper function. >> diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c >> index 3417e1ac7918..a98a4aad5037 100644 >> --- a/drivers/gpu/drm/drm_vblank.c >> +++ b/drivers/gpu/drm/drm_vblank.c >> @@ -1748,8 +1748,13 @@ int drm_wait_vblank_ioctl(struct drm_device *dev, void *data, >> unsigned int pipe_index; >> unsigned int flags, pipe, high_pipe; >> >> - if (!dev->irq_enabled) >> - return -EOPNOTSUPP; >> + if (drm_core_check_feature(dev, DRIVER_MODESET)) { >> + if (!drm_dev_has_vblank(dev)) >> + return -EOPNOTSUPP; >> + } else { >> + if (!dev->irq_enabled) >> + return -EOPNOTSUPP; >> + } > > For a system call that is used quite a lot by userspace we have increased the code size > in a noticeable way. Can we not cache it privately? I'm not quite sure that I understand your concern. The additionally called functions are trivial one-liners; probably inlined anyway. However, irq_enabled is only relevant for legacy drivers and will eventually disappear behind CONFIG_DRM_LEGACY. We can rewrite the test like this: ifdef CONFIG_DRM_LEGACY if (unlikely(check_feature(dev, DRIVER_LEGACY))) { if (!irq_enabled) return; } else #endif { if (!has_vblank_support(dev)) return; } As CONFIG_DRM_LEGACY is most likely disabled on concurrent systems, we'd get a single test for the modern drivers. If DRM_LEGACYis on, the compiler at least knows that the else branch is preferred. Best regards Thomas
Hi Thomas, On Wed, Jun 23, 2021 at 08:43:07AM +0200, Thomas Zimmermann wrote: > Hi Liviu > > Am 22.06.21 um 17:25 schrieb Liviu Dudau: > > Hello, > > > > On Tue, Jun 22, 2021 at 04:09:44PM +0200, Thomas Zimmermann wrote: > > > For KMS drivers, replace the IRQ check in VBLANK ioctls with a check for > > > vblank support. IRQs might be enabled wthout vblanking being supported. > > > > > > This change also removes the DRM framework's only dependency on IRQ state > > > for non-legacy drivers. For legacy drivers with userspace modesetting, > > > the original test remains in drm_wait_vblank_ioctl(). > > > > > > v2: > > > * keep the old test for legacy drivers in > > > drm_wait_vblank_ioctl() (Daniel) > > > > > > Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> > > > --- > > > drivers/gpu/drm/drm_irq.c | 10 +++------- > > > drivers/gpu/drm/drm_vblank.c | 13 +++++++++---- > > > 2 files changed, 12 insertions(+), 11 deletions(-) > > > > > > diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c > > > index c3bd664ea733..1d7785721323 100644 > > > --- a/drivers/gpu/drm/drm_irq.c > > > +++ b/drivers/gpu/drm/drm_irq.c > > > @@ -74,10 +74,8 @@ > > > * only supports devices with a single interrupt on the main device stored in > > > * &drm_device.dev and set as the device paramter in drm_dev_alloc(). > > > * > > > - * These IRQ helpers are strictly optional. Drivers which roll their own only > > > - * need to set &drm_device.irq_enabled to signal the DRM core that vblank > > > - * interrupts are working. Since these helpers don't automatically clean up the > > > - * requested interrupt like e.g. devm_request_irq() they're not really > > > + * These IRQ helpers are strictly optional. Since these helpers don't automatically > > > + * clean up the requested interrupt like e.g. devm_request_irq() they're not really > > > * recommended. > > > */ > > > @@ -91,9 +89,7 @@ > > > * and after the installation. > > > * > > > * This is the simplified helper interface provided for drivers with no special > > > - * needs. Drivers which need to install interrupt handlers for multiple > > > - * interrupts must instead set &drm_device.irq_enabled to signal the DRM core > > > - * that vblank interrupts are available. > > > + * needs. > > > * > > > * @irq must match the interrupt number that would be passed to request_irq(), > > > * if called directly instead of using this helper function. > > > diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c > > > index 3417e1ac7918..a98a4aad5037 100644 > > > --- a/drivers/gpu/drm/drm_vblank.c > > > +++ b/drivers/gpu/drm/drm_vblank.c > > > @@ -1748,8 +1748,13 @@ int drm_wait_vblank_ioctl(struct drm_device *dev, void *data, > > > unsigned int pipe_index; > > > unsigned int flags, pipe, high_pipe; > > > - if (!dev->irq_enabled) > > > - return -EOPNOTSUPP; > > > + if (drm_core_check_feature(dev, DRIVER_MODESET)) { > > > + if (!drm_dev_has_vblank(dev)) > > > + return -EOPNOTSUPP; > > > + } else { > > > + if (!dev->irq_enabled) > > > + return -EOPNOTSUPP; > > > + } > > > > For a system call that is used quite a lot by userspace we have increased the code size > > in a noticeable way. Can we not cache it privately? > > I'm not quite sure that I understand your concern. The additionally called > functions are trivial one-liners; probably inlined anyway. They are inlined. However we replace the pointer dereference (which can be calculated at compile time as offset from a base pointer) with the code in drm_core_check_all_features() that does 3 pointer dereferences, masking and logical AND before checking for matching value. > > However, irq_enabled is only relevant for legacy drivers and will eventually > disappear behind CONFIG_DRM_LEGACY. We can rewrite the test like this: I get the point that irq_enabled is legacy. However the IOCTL call is not and usually is used in time critical code to wait for vblank before starting the old buffers for a new frame. At 60Hz that's probably less of a concern, but at 120Hz refresh rate and reduced vblank time your time slice allocation for new work matters. Best regards, Liviu > > ifdef CONFIG_DRM_LEGACY > if (unlikely(check_feature(dev, DRIVER_LEGACY))) { > if (!irq_enabled) > return; > } else > #endif > { > if (!has_vblank_support(dev)) > return; > } > > As CONFIG_DRM_LEGACY is most likely disabled on concurrent systems, we'd get > a single test for the modern drivers. If DRM_LEGACYis on, the compiler at > least knows that the else branch is preferred. > > Best regards > Thomas > > -- > 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_irq.c b/drivers/gpu/drm/drm_irq.c index c3bd664ea733..1d7785721323 100644 --- a/drivers/gpu/drm/drm_irq.c +++ b/drivers/gpu/drm/drm_irq.c @@ -74,10 +74,8 @@ * only supports devices with a single interrupt on the main device stored in * &drm_device.dev and set as the device paramter in drm_dev_alloc(). * - * These IRQ helpers are strictly optional. Drivers which roll their own only - * need to set &drm_device.irq_enabled to signal the DRM core that vblank - * interrupts are working. Since these helpers don't automatically clean up the - * requested interrupt like e.g. devm_request_irq() they're not really + * These IRQ helpers are strictly optional. Since these helpers don't automatically + * clean up the requested interrupt like e.g. devm_request_irq() they're not really * recommended. */ @@ -91,9 +89,7 @@ * and after the installation. * * This is the simplified helper interface provided for drivers with no special - * needs. Drivers which need to install interrupt handlers for multiple - * interrupts must instead set &drm_device.irq_enabled to signal the DRM core - * that vblank interrupts are available. + * needs. * * @irq must match the interrupt number that would be passed to request_irq(), * if called directly instead of using this helper function. diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c index 3417e1ac7918..a98a4aad5037 100644 --- a/drivers/gpu/drm/drm_vblank.c +++ b/drivers/gpu/drm/drm_vblank.c @@ -1748,8 +1748,13 @@ int drm_wait_vblank_ioctl(struct drm_device *dev, void *data, unsigned int pipe_index; unsigned int flags, pipe, high_pipe; - if (!dev->irq_enabled) - return -EOPNOTSUPP; + if (drm_core_check_feature(dev, DRIVER_MODESET)) { + if (!drm_dev_has_vblank(dev)) + return -EOPNOTSUPP; + } else { + if (!dev->irq_enabled) + return -EOPNOTSUPP; + } if (vblwait->request.type & _DRM_VBLANK_SIGNAL) return -EINVAL; @@ -2023,7 +2028,7 @@ int drm_crtc_get_sequence_ioctl(struct drm_device *dev, void *data, if (!drm_core_check_feature(dev, DRIVER_MODESET)) return -EOPNOTSUPP; - if (!dev->irq_enabled) + if (!drm_dev_has_vblank(dev)) return -EOPNOTSUPP; crtc = drm_crtc_find(dev, file_priv, get_seq->crtc_id); @@ -2082,7 +2087,7 @@ int drm_crtc_queue_sequence_ioctl(struct drm_device *dev, void *data, if (!drm_core_check_feature(dev, DRIVER_MODESET)) return -EOPNOTSUPP; - if (!dev->irq_enabled) + if (!drm_dev_has_vblank(dev)) return -EOPNOTSUPP; crtc = drm_crtc_find(dev, file_priv, queue_seq->crtc_id);
For KMS drivers, replace the IRQ check in VBLANK ioctls with a check for vblank support. IRQs might be enabled wthout vblanking being supported. This change also removes the DRM framework's only dependency on IRQ state for non-legacy drivers. For legacy drivers with userspace modesetting, the original test remains in drm_wait_vblank_ioctl(). v2: * keep the old test for legacy drivers in drm_wait_vblank_ioctl() (Daniel) Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> --- drivers/gpu/drm/drm_irq.c | 10 +++------- drivers/gpu/drm/drm_vblank.c | 13 +++++++++---- 2 files changed, 12 insertions(+), 11 deletions(-)