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