drm/radeon/kms: add some loop timeouts in pageflip code

Avoid infinite loops waiting for surface updates if a GPU
reset happens while waiting for a page flip.

See:
https://bugs.freedesktop.org/show_bug.cgi?id=43191

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@kernel.org
Reviewed-by: Mario Kleiner <mario.kleiner@tuebingen.mpg.de>
Tested-by: Simon Farnsworth <simon.farnsworth@onelan.co.uk>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/drivers/gpu/drm/radeon/r100.c b/drivers/gpu/drm/radeon/r100.c
index ad158ea49901..bfc08f6320f8 100644
--- a/drivers/gpu/drm/radeon/r100.c
+++ b/drivers/gpu/drm/radeon/r100.c
@@ -187,13 +187,18 @@ u32 r100_page_flip(struct radeon_device *rdev, int crtc_id, u64 crtc_base)
 {
         struct radeon_crtc *radeon_crtc = rdev->mode_info.crtcs[crtc_id];
         u32 tmp = ((u32)crtc_base) | RADEON_CRTC_OFFSET__OFFSET_LOCK;
+        int i;
 
         /* Lock the graphics update lock */
         /* update the scanout addresses */
         WREG32(RADEON_CRTC_OFFSET + radeon_crtc->crtc_offset, tmp);
 
         /* Wait for update_pending to go high. */
-        while (!(RREG32(RADEON_CRTC_OFFSET + radeon_crtc->crtc_offset) & RADEON_CRTC_OFFSET__GUI_TRIG_OFFSET));
+        for (i = 0; i < rdev->usec_timeout; i++) {
+                if (RREG32(RADEON_CRTC_OFFSET + radeon_crtc->crtc_offset) & RADEON_CRTC_OFFSET__GUI_TRIG_OFFSET)
+                        break;
+                udelay(1);
+        }
         DRM_DEBUG("Update pending now high. Unlocking vupdate_lock.\n");
 
         /* Unlock the lock, so double-buffering can take place inside vblank */