drm/radeon: do a posting read in rs600_set_irq

commit 54acf107e4e66d1f4a697e08a7f60dba9fcf07c3 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/rs600.c b/drivers/gpu/drm/radeon/rs600.c
index d6e64b93d8b1f3585087f8fa28a1c574e2a8d503..1016f53f755cc0e0af8f3a49c1b59d9b4cc985e7 100644 (file)
--- a/drivers/gpu/drm/radeon/rs600.c
+++ b/drivers/gpu/drm/radeon/rs600.c
@@ -684,6 +684,10 @@ int rs600_irq_set(struct radeon_device *rdev)
        WREG32(R_007D18_DC_HOT_PLUG_DETECT2_INT_CONTROL, hpd2);
        if (ASIC_IS_DCE2(rdev))
                WREG32(R_007408_HDMI0_AUDIO_PACKET_CONTROL, hdmi0);
+
+       /* posting read */
+       RREG32(R_000040_GEN_INT_CNTL);
+
        return 0;
 }