drm/radeon/dpm: disable ss on Cayman

commit c745fe611ca42295c9d91d8e305d27983e9132ef upstream.

Spread spectrum seems to cause hangs when dynamic clock
switching is enabled.  Disable it for now. This does not
affect performance or the amount of power saved. Tracked
down by Martin Andersson.

bug:
https://bugs.freedesktop.org/show_bug.cgi?id=69723

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/radeon/rv770_dpm.c b/drivers/gpu/drm/radeon/rv770_dpm.c
index 913b025ae9b399695bed47af97cccf08fe68caf7..374499db20c7e59b55d956b066a30bdc42b4f71f 100644 (file)
--- a/drivers/gpu/drm/radeon/rv770_dpm.c
+++ b/drivers/gpu/drm/radeon/rv770_dpm.c
@@ -2328,6 +2328,12 @@ void rv770_get_engine_memory_ss(struct radeon_device *rdev)
        pi->mclk_ss = radeon_atombios_get_asic_ss_info(rdev, &ss,
                                                       ASIC_INTERNAL_MEMORY_SS, 0);
 
+       /* disable ss, causes hangs on some cayman boards */
+       if (rdev->family == CHIP_CAYMAN) {
+               pi->sclk_ss = false;
+               pi->mclk_ss = false;
+       }
+
        if (pi->sclk_ss || pi->mclk_ss)
                pi->dynamic_ss = true;
        else