drm: Stop using drm_vblank_count() as the hw frame counter

drm_vblank_count() returns the software counter. We should not pretend
it's the hw counter since we use the hw counter to figuere out what the
software counter value should be. So instead provide a new function
drm_vblank_no_hw_counter() for drivers that don't have a real hw
counter. The new function simply returns 0, which is about the only
thing it can do.

Cc: Vincent Abriou <vincent.abriou@st.com>
Cc: Thierry Reding <treding@nvidia.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Vincent Abriou <vincent.abriou@st.com>
[danvet: s/int pipe/unsigned int pipe/ to follow Thierry's interface
change.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 17 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index 0659d9956b7c..7bdf247b9681 100644
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -1798,3 +1798,20 @@ bool drm_crtc_handle_vblank(struct drm_crtc *crtc)
 	return drm_handle_vblank(crtc->dev, drm_crtc_index(crtc));
 }
 EXPORT_SYMBOL(drm_crtc_handle_vblank);
+
+/**
+ * drm_vblank_no_hw_counter - "No hw counter" implementation of .get_vblank_counter()
+ * @dev: DRM device
+ * @pipe: CRTC for which to read the counter
+ *
+ * Drivers can plug this into the .get_vblank_counter() function if
+ * there is no useable hardware frame counter available.
+ *
+ * Returns:
+ * 0
+ */
+u32 drm_vblank_no_hw_counter(struct drm_device *dev, unsigned int pipe)
+{
+	return 0;
+}
+EXPORT_SYMBOL(drm_vblank_no_hw_counter);