drm/radeon: do a posting read in r600_set_irq

To make sure the writes go through the pci bridge.

bug:
https://bugzilla.kernel.org/show_bug.cgi?id=90741

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/gpu/drm/radeon/r600.c b/drivers/gpu/drm/radeon/r600.c
index 07a71a2488c9..2fcad344492f 100644
--- a/drivers/gpu/drm/radeon/r600.c
+++ b/drivers/gpu/drm/radeon/r600.c
@@ -3784,6 +3784,9 @@ int r600_irq_set(struct radeon_device *rdev)
                 WREG32(RV770_CG_THERMAL_INT, thermal_int);
         }
 
+        /* posting read */
+        RREG32(R_000E50_SRBM_STATUS);
+
         return 0;
 }