drm/radeon: use pflip irq on R600+ v2

Testing the update pending bit directly after issuing an
update is nonsense cause depending on the pixel clock the
CRTC needs a bit of time to execute the flip even when we
are in the VBLANK period.

This is just a non invasive patch to solve the problem at
hand, a more complete and cleaner solution should follow
in the next merge window.

Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=76564

v2: fix source IDs for CRTC2-6

Signed-off-by: Christian König <christian.koenig@amd.com>
Cc: stable@vger.kernel.org

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/gpu/drm/radeon/radeon_display.c b/drivers/gpu/drm/radeon/radeon_display.c
index 8d99d5ee8014..14bd701e316c 100644
--- a/drivers/gpu/drm/radeon/radeon_display.c
+++ b/drivers/gpu/drm/radeon/radeon_display.c
@@ -284,6 +284,10 @@ void radeon_crtc_handle_flip(struct radeon_device *rdev, int crtc_id)
         u32 update_pending;
         int vpos, hpos;
 
+        /* can happen during initialization */
+        if (radeon_crtc == NULL)
+                return;
+
         spin_lock_irqsave(&rdev->ddev->event_lock, flags);
         work = radeon_crtc->unpin_work;
         if (work == NULL ||