drm/radeon: do a posting read in r100_set_irq

[ Upstream commit f957063fee6392bb9365370db6db74dc0b2dce0a ]

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
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>

diff --git a/drivers/gpu/drm/radeon/r100.c b/drivers/gpu/drm/radeon/r100.c
index cdf6e2149539283cf46ccb0cd3e1d5cb650b253f..a959cc1e7c8eb3fd99e5b98b1af8b9bec8eabe65 100644 (file)
--- a/drivers/gpu/drm/radeon/r100.c
+++ b/drivers/gpu/drm/radeon/r100.c
@@ -728,6 +728,10 @@ int r100_irq_set(struct radeon_device *rdev)
                tmp |= RADEON_FP2_DETECT_MASK;
        }
        WREG32(RADEON_GEN_INT_CNTL, tmp);
+
+       /* read back to post the write */
+       RREG32(RADEON_GEN_INT_CNTL);
+
        return 0;
 }