drm/radeon: do a posting read in r600_set_irq

commit 9d1393f23d5656cdd5f368efd60694d4aeed81d3 upstream.

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>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

diff --git a/drivers/gpu/drm/radeon/r600.c b/drivers/gpu/drm/radeon/r600.c
index 44b046b4056feb8d0bc8fa915e3a36649147508d..5e31413fb454a179c56d0d8c8ed3efbf1833ee9b 100644 (file)
--- a/drivers/gpu/drm/radeon/r600.c
+++ b/drivers/gpu/drm/radeon/r600.c
@@ -3637,6 +3637,9 @@ int r600_irq_set(struct radeon_device *rdev)
                WREG32(RV770_CG_THERMAL_INT, thermal_int);
        }
 
+       /* posting read */
+       RREG32(R_000E50_SRBM_STATUS);
+
        return 0;
 }