[PATCH v2 13/19] drm: Kick start vblank interrupts at drm_vblank_on()

[ville.syrjala at linux.intel.com]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

If the user is interested in getting accurate vblank sequence
numbers all the time they may disable the vblank disable timer
entirely. In that case it seems appropriate to kick start the
vblank interrupts already from drm_vblank_on().

v2: Adapt to the drm_vblank_offdelay ==0 vs <0 changes

Reviewed-by: Matt Roper <matthew.d.roper at intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/drm_irq.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c
index 8dbcc3f..af33df1 100644
--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -1126,9 +1126,12 @@ void drm_vblank_on(struct drm_device *dev, int crtc)
 	vblank->last =
 		(dev->driver->get_vblank_counter(dev, crtc) - 1) &
 		dev->max_vblank_count;
-
-	/* re-enable interrupts if there's are users left */
-	if (atomic_read(&vblank->refcount) != 0)
+	/*
+	 * re-enable interrupts if there are users left, or the
+	 * user wishes vblank interrupts to be enabled all the time.
+	 */
+	if (atomic_read(&vblank->refcount) != 0 ||
+	    (!dev->vblank_disable_immediate && drm_vblank_offdelay == 0))
 		WARN_ON(drm_vblank_enable(dev, crtc));
 	spin_unlock_irqrestore(&dev->vbl_lock, irqflags);
 }
-- 
1.8.5.5