drm/radeon/dpm: implement force performance levels for rv6xx

Allows you to limit the selected power levels via sysfs.
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/radeon_asic.c

@@ -1161,6 +1161,7 @@ static struct radeon_asic rv6xx_asic = {
 		.get_mclk = &rv6xx_dpm_get_mclk,
 		.print_power_state = &rv6xx_dpm_print_power_state,
 		.debugfs_print_current_performance_level = &rv6xx_dpm_debugfs_print_current_performance_level,
+		.force_performance_level = &rv6xx_dpm_force_performance_level,
 	},
 	.pflip = {
 		.pre_page_flip = &rs600_pre_page_flip,

drivers/gpu/drm/radeon/radeon_asic.h

@@ -421,6 +421,8 @@ void rv6xx_dpm_print_power_state(struct radeon_device *rdev,
 				 struct radeon_ps *ps);
 void rv6xx_dpm_debugfs_print_current_performance_level(struct radeon_device *rdev,
 						       struct seq_file *m);
+int rv6xx_dpm_force_performance_level(struct radeon_device *rdev,
+				      enum radeon_dpm_forced_level level);
 /* rs780 dpm */
 int rs780_dpm_init(struct radeon_device *rdev);
 int rs780_dpm_enable(struct radeon_device *rdev);

drivers/gpu/drm/radeon/rv6xx_dpm.c

@@ -1670,6 +1670,8 @@ int rv6xx_dpm_set_power_state(struct radeon_device *rdev)
 	struct radeon_ps *old_ps = rdev->pm.dpm.current_ps;
 	int ret;
 
+	pi->restricted_levels = 0;
+
 	rv6xx_set_uvd_clock_before_set_eng_clock(rdev, new_ps, old_ps);
 
 	rv6xx_clear_vc(rdev);
@@ -1756,6 +1758,8 @@ int rv6xx_dpm_set_power_state(struct radeon_device *rdev)
 
 	rv6xx_set_uvd_clock_after_set_eng_clock(rdev, new_ps, old_ps);
 
+	rdev->pm.dpm.forced_level = RADEON_DPM_FORCED_LEVEL_AUTO;
+
 	return 0;
 }
 
@@ -2085,3 +2089,34 @@ u32 rv6xx_dpm_get_mclk(struct radeon_device *rdev, bool low)
 	else
 		return requested_state->high.mclk;
 }
+
+int rv6xx_dpm_force_performance_level(struct radeon_device *rdev,
+				      enum radeon_dpm_forced_level level)
+{
+	struct rv6xx_power_info *pi = rv6xx_get_pi(rdev);
+
+	if (level == RADEON_DPM_FORCED_LEVEL_HIGH) {
+		pi->restricted_levels = 3;
+	} else if (level == RADEON_DPM_FORCED_LEVEL_LOW) {
+		pi->restricted_levels = 2;
+	} else {
+		pi->restricted_levels = 0;
+	}
+
+	rv6xx_clear_vc(rdev);
+	r600_power_level_enable(rdev, R600_POWER_LEVEL_LOW, true);
+	r600_set_at(rdev, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF);
+	r600_wait_for_power_level(rdev, R600_POWER_LEVEL_LOW);
+	r600_power_level_enable(rdev, R600_POWER_LEVEL_HIGH, false);
+	r600_power_level_enable(rdev, R600_POWER_LEVEL_MEDIUM, false);
+	rv6xx_enable_medium(rdev);
+	rv6xx_enable_high(rdev);
+	if (pi->restricted_levels == 3)
+		r600_power_level_enable(rdev, R600_POWER_LEVEL_LOW, false);
+	rv6xx_program_vc(rdev);
+	rv6xx_program_at(rdev);
+
+	rdev->pm.dpm.forced_level = level;
+
+	return 0;
+}