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=73931

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

2 files changed, 35 insertions, 28 deletions

diff --git a/drivers/gpu/drm/radeon/r600_dpm.c b/drivers/gpu/drm/radeon/r600_dpm.c
index cbf7e3269f8..9c61b74ef44 100644
--- a/drivers/gpu/drm/radeon/r600_dpm.c
+++ b/drivers/gpu/drm/radeon/r600_dpm.c
@@ -158,16 +158,18 @@ 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 */
 
-	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) {
-			line_time_us = (radeon_crtc->hw_mode.crtc_htotal * 1000) /
-				radeon_crtc->hw_mode.clock;
-			vblank_lines = radeon_crtc->hw_mode.crtc_vblank_end -
-				radeon_crtc->hw_mode.crtc_vdisplay +
-				(radeon_crtc->v_border * 2);
-			vblank_time_us = vblank_lines * line_time_us;
-			break;
+	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) {
+				line_time_us = (radeon_crtc->hw_mode.crtc_htotal * 1000) /
+					radeon_crtc->hw_mode.clock;
+				vblank_lines = radeon_crtc->hw_mode.crtc_vblank_end -
+					radeon_crtc->hw_mode.crtc_vdisplay +
+					(radeon_crtc->v_border * 2);
+				vblank_time_us = vblank_lines * line_time_us;
+				break;
+			}
 		}
 	}
 
@@ -181,14 +183,15 @@ u32 r600_dpm_get_vrefresh(struct radeon_device *rdev)
 	struct radeon_crtc *radeon_crtc;
 	u32 vrefresh = 0;
 
-	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) {
-			vrefresh = radeon_crtc->hw_mode.vrefresh;
-			break;
+	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) {
+				vrefresh = radeon_crtc->hw_mode.vrefresh;
+				break;
+			}
 		}
 	}
-
 	return vrefresh;
 }
 
diff --git a/drivers/gpu/drm/radeon/radeon_pm.c b/drivers/gpu/drm/radeon/radeon_pm.c
index d79895aebc5..6fac8efe834 100644
--- a/drivers/gpu/drm/radeon/radeon_pm.c
+++ b/drivers/gpu/drm/radeon/radeon_pm.c
@@ -1406,12 +1406,14 @@ static void radeon_pm_compute_clocks_old(struct radeon_device *rdev)
 
 	rdev->pm.active_crtcs = 0;
 	rdev->pm.active_crtc_count = 0;
-	list_for_each_entry(crtc,
-		&ddev->mode_config.crtc_list, head) {
-		radeon_crtc = to_radeon_crtc(crtc);
-		if (radeon_crtc->enabled) {
-			rdev->pm.active_crtcs |= (1 << radeon_crtc->crtc_id);
-			rdev->pm.active_crtc_count++;
+	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);
+			if (radeon_crtc->enabled) {
+				rdev->pm.active_crtcs |= (1 << radeon_crtc->crtc_id);
+				rdev->pm.active_crtc_count++;
+			}
 		}
 	}
 
@@ -1478,12 +1480,14 @@ 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;
-	list_for_each_entry(crtc,
-		&ddev->mode_config.crtc_list, head) {
-		radeon_crtc = to_radeon_crtc(crtc);
-		if (crtc->enabled) {
-			rdev->pm.dpm.new_active_crtcs |= (1 << radeon_crtc->crtc_id);
-			rdev->pm.dpm.new_active_crtc_count++;
+	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);
+			if (crtc->enabled) {
+				rdev->pm.dpm.new_active_crtcs |= (1 << radeon_crtc->crtc_id);
+				rdev->pm.dpm.new_active_crtc_count++;
+			}
 		}
 	}