drm/radeon/pm: don't walk the crtc list before it has been initialized (v2)

Avoids a crash in certain cases when thermal irqs are generated
before the display structures have been initialized.

v2: fix the vblank and vrefresh helpers as well

bug:
https://bugzilla.kernel.org/show_bug.cgi?id=73931Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

drivers/gpu/drm/radeon/r600_dpm.c

@@ -158,6 +158,7 @@ u32 r600_dpm_get_vblank_time(struct radeon_device *rdev)
 	u32 line_time_us, vblank_lines;
 	u32 vblank_time_us = 0xffffffff; /* if the displays are off, vblank time is max */
 
+	if (rdev->num_crtc && rdev->mode_info.mode_config_initialized) {
 		list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
 			radeon_crtc = to_radeon_crtc(crtc);
 			if (crtc->enabled && radeon_crtc->enabled && radeon_crtc->hw_mode.clock) {
@@ -170,6 +171,7 @@ u32 r600_dpm_get_vblank_time(struct radeon_device *rdev)
 				break;
 			}
 		}
+	}
 
 	return vblank_time_us;
 }
@@ -181,6 +183,7 @@ u32 r600_dpm_get_vrefresh(struct radeon_device *rdev)
 	struct radeon_crtc *radeon_crtc;
 	u32 vrefresh = 0;
 
+	if (rdev->num_crtc && rdev->mode_info.mode_config_initialized) {
 		list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
 			radeon_crtc = to_radeon_crtc(crtc);
 			if (crtc->enabled && radeon_crtc->enabled && radeon_crtc->hw_mode.clock) {
@@ -188,7 +191,7 @@ u32 r600_dpm_get_vrefresh(struct radeon_device *rdev)
 				break;
 			}
 		}
-
+	}
 	return vrefresh;
 }
 

drivers/gpu/drm/radeon/radeon_pm.c

@@ -1406,6 +1406,7 @@ static void radeon_pm_compute_clocks_old(struct radeon_device *rdev)
 
 	rdev->pm.active_crtcs = 0;
 	rdev->pm.active_crtc_count = 0;
+	if (rdev->num_crtc && rdev->mode_info.mode_config_initialized) {
 		list_for_each_entry(crtc,
 				    &ddev->mode_config.crtc_list, head) {
 			radeon_crtc = to_radeon_crtc(crtc);
@@ -1414,6 +1415,7 @@ static void radeon_pm_compute_clocks_old(struct radeon_device *rdev)
 				rdev->pm.active_crtc_count++;
 			}
 		}
+	}
 
 	if (rdev->pm.pm_method == PM_METHOD_PROFILE) {
 		radeon_pm_update_profile(rdev);
@@ -1478,6 +1480,7 @@ static void radeon_pm_compute_clocks_dpm(struct radeon_device *rdev)
 	/* update active crtc counts */
 	rdev->pm.dpm.new_active_crtcs = 0;
 	rdev->pm.dpm.new_active_crtc_count = 0;
+	if (rdev->num_crtc && rdev->mode_info.mode_config_initialized) {
 		list_for_each_entry(crtc,
 				    &ddev->mode_config.crtc_list, head) {
 			radeon_crtc = to_radeon_crtc(crtc);
@@ -1486,6 +1489,7 @@ static void radeon_pm_compute_clocks_dpm(struct radeon_device *rdev)
 				rdev->pm.dpm.new_active_crtc_count++;
 			}
 		}
+	}
 
 	/* update battery/ac status */
 	if (power_supply_is_system_supplied() > 0)