On 14.01.13 17:05, Thierry Reding wrote:
Implement support for the VBLANK IOCTL. Note that Tegra is somewhat
special in this case because it doesn't use the generic IRQ support
provided by the DRM core (DRIVER_HAVE_IRQ) but rather registers one
interrupt handler for each display controller.
While at it, clean up the way that interrupts are enabled to ensure
that the VBLANK interrupt only gets enabled when required.
Signed-off-by: Thierry Reding <thierry.reding@xxxxxxxxxxxxxxxxx>
... snip ...
struct drm_driver tegra_drm_driver = {
.driver_features = DRIVER_BUS_PLATFORM | DRIVER_MODESET | DRIVER_GEM,
.load = tegra_drm_load,
@@ -96,6 +136,10 @@ struct drm_driver tegra_drm_driver = {
.open = tegra_drm_open,
.lastclose = tegra_drm_lastclose,
+ .get_vblank_counter = drm_vblank_count,
-> .get_vblank_counter = drm_vblank_count is a no-op.
.get_vblank_counter() is supposed to return some real hardware vblank
counter value to reinitialize the software vblank counter at vbl irq
enable time. That software counter gets queried via drm_vblank_count().
If you hook this up to drm_vblank_count() it essentially returns a
constant, frozen vblank count, it has the same effect as returning zero
or any other constant value -- You lose all vblank counter increments
during vblank irq off time. The same problem is present in nouveau-kms.
I think it would be better to either implement a real hw counter query,
or some function with a /* TODO: Implement me properly */ comment which
returns zero, so it is clear something is missing here.
thanks,
-mario
+ .enable_vblank = tegra_drm_enable_vblank,
+ .disable_vblank = tegra_drm_disable_vblank,
+
.gem_free_object = drm_gem_cma_free_object,
.gem_vm_ops = &drm_gem_cma_vm_ops,
.dumb_create = drm_gem_cma_dumb_create,
diff --git a/drivers/gpu/drm/tegra/drm.h b/drivers/gpu/drm/tegra/drm.h
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