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 cbf7e3269f84..9c61b74ef441 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 d79895aebc59..6fac8efe8340 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++;
+                        }
                 }
         }