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: Zefan Li <lizefan@huawei.com>

diff --git a/drivers/gpu/drm/radeon/r600.c b/drivers/gpu/drm/radeon/r600.c
index 1555cd69411179da610522f740bfe3f34a58d0ad..9c7062d970ee742299465dcbf0046ab5e64022d5 100644 (file)
--- a/drivers/gpu/drm/radeon/r600.c
+++ b/drivers/gpu/drm/radeon/r600.c
@@ -3184,6 +3184,9 @@ int r600_irq_set(struct radeon_device *rdev)
                WREG32(DC_HOT_PLUG_DETECT3_INT_CONTROL, hpd3);
        }
 
+       /* posting read */
+       RREG32(R_000E50_SRBM_STATUS);
+
        return 0;
 }