@@ -434,7 +434,7 @@ struct drm_driver {
*
* Driver callback for fetching a raw hardware vblank counter for @crtc.
* If a device doesn't have a hardware counter, the driver can simply
- * return the value of drm_vblank_count. The DRM core will account for
+ * use drm_vblank_no_hw_counter() function. The DRM core will account for
* missed vblank events while interrupts where disabled based on system
* timestamps.
*
@@ -452,8 +452,8 @@ struct drm_driver {
* @pipe: which irq to enable
*
* Enable vblank interrupts for @crtc. If the device doesn't have
- * a hardware vblank counter, this routine should be a no-op, since
- * interrupts will have to stay on to keep the count accurate.
+ * a hardware vblank counter, the driver should use the
+ * drm_vblank_no_hw_counter() function that keeps a virtual counter.
*
* RETURNS
* Zero on success, appropriate errno if the given @crtc's vblank
@@ -467,8 +467,8 @@ struct drm_driver {
* @pipe: which irq to enable
*
* Disable vblank interrupts for @crtc. If the device doesn't have
- * a hardware vblank counter, this routine should be a no-op, since
- * interrupts will have to stay on to keep the count accurate.
+ * a hardware vblank counter, the driver should use the
+ * drm_vblank_no_hw_counter() function that keeps a virtual counter.
*/
void (*disable_vblank) (struct drm_device *dev, unsigned int pipe);
Since commit 4dfd64862ff8 ("drm: Use vblank timestamps to guesstimate how many vblanks were missed"), the DRM framework can cope with devices that don't have a hardware counter for vsync events without having to keep the vsync interrupts enabled all the time. Drivers handling such hardware should use drm_vblank_no_hw_counter() function for their ->get_vblank_counter hook. Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com> --- include/drm/drmP.h | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)