drm/radeon/r6xx: add a stubbed out set_uvd_clocks callback

Certain r6xx boards use the same power state for both UVD
and other things.  Since we don't support UVD on r6xx boards
at the moment, there was no callback installed for setting
the UVD clocks, however, on systems that use the same power
state, this leads to a NULL pointer dereference.  Fill
in a stubbed out implementation for now to avoid the crash.

Fixes:
https://bugs.freedesktop.org/show_bug.cgi?id=66963

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: "3.11" <stable@vger.kernel.org>

drivers/gpu/drm/radeon/r600.c

@@ -119,6 +119,11 @@ u32 r600_get_xclk(struct radeon_device *rdev)
 	return rdev->clock.spll.reference_freq;
 }
 
+int r600_set_uvd_clocks(struct radeon_device *rdev, u32 vclk, u32 dclk)
+{
+	return 0;
+}
+
 /* get temperature in millidegrees */
 int rv6xx_get_temp(struct radeon_device *rdev)
 {

drivers/gpu/drm/radeon/radeon_asic.c

@@ -1037,6 +1037,7 @@ static struct radeon_asic rv6xx_asic = {
 		.set_pcie_lanes = &r600_set_pcie_lanes,
 		.set_clock_gating = NULL,
 		.get_temperature = &rv6xx_get_temp,
+		.set_uvd_clocks = &r600_set_uvd_clocks,
 	},
 	.dpm = {
 		.init = &rv6xx_dpm_init,
@@ -1126,6 +1127,7 @@ static struct radeon_asic rs780_asic = {
 		.set_pcie_lanes = NULL,
 		.set_clock_gating = NULL,
 		.get_temperature = &rv6xx_get_temp,
+		.set_uvd_clocks = &r600_set_uvd_clocks,
 	},
 	.dpm = {
 		.init = &rs780_dpm_init,

drivers/gpu/drm/radeon/radeon_asic.h

@@ -389,6 +389,7 @@ int r600_mc_wait_for_idle(struct radeon_device *rdev);
 u32 r600_get_xclk(struct radeon_device *rdev);
 uint64_t r600_get_gpu_clock_counter(struct radeon_device *rdev);
 int rv6xx_get_temp(struct radeon_device *rdev);
+int r600_set_uvd_clocks(struct radeon_device *rdev, u32 vclk, u32 dclk);
 int r600_dpm_pre_set_power_state(struct radeon_device *rdev);
 void r600_dpm_post_set_power_state(struct radeon_device *rdev);
 /* r600 dma */