There is possible circular locking dependency detected on event_mutex.
To break this possible circular locking, this patch move setting fail
safe mode out of event_mutex scope.
Fixes: d4aca422539c ("drm/msm/dp: always add fail-safe mode into connector mode list")
Signed-off-by: Kuogee Hsieh <quic_khsieh@xxxxxxxxxxx>
---
drivers/gpu/drm/msm/dp/dp_display.c | 6 ++++++
drivers/gpu/drm/msm/dp/dp_panel.c | 20 ++++++++++----------
drivers/gpu/drm/msm/dp/dp_panel.h | 1 +
3 files changed, 17 insertions(+), 10 deletions(-)
diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
index 178b774..a42732b 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -580,6 +580,12 @@ static int dp_hpd_plug_handle(struct dp_display_private *dp, u32 data)
dp->dp_display.connector_type, state);
mutex_unlock(&dp->event_mutex);
+ /*
+ * add fail safe mode outside event_mutex scope
+ * to avoid potiential circular lock with drm thread
+ */
+ dp_panel_add_fail_safe_mode(dp->dp_display.connector);
+
/* uevent will complete connection part */
return 0;
};
diff --git a/drivers/gpu/drm/msm/dp/dp_panel.c b/drivers/gpu/drm/msm/dp/dp_panel.c
index f141872..26c3653 100644
--- a/drivers/gpu/drm/msm/dp/dp_panel.c
+++ b/drivers/gpu/drm/msm/dp/dp_panel.c
@@ -151,6 +151,15 @@ static int dp_panel_update_modes(struct drm_connector *connector,
return rc;
}
+void dp_panel_add_fail_safe_mode(struct drm_connector *connector)
+{
+ /* fail safe edid */
+ mutex_lock(&connector->dev->mode_config.mutex);
+ if (drm_add_modes_noedid(connector, 640, 480))
+ drm_set_preferred_mode(connector, 640, 480);
+ mutex_unlock(&connector->dev->mode_config.mutex);
+}
+
int dp_panel_read_sink_caps(struct dp_panel *dp_panel,
struct drm_connector *connector)
{
@@ -207,16 +216,7 @@ int dp_panel_read_sink_caps(struct dp_panel *dp_panel,
goto end;
}
- /* fail safe edid */
- mutex_lock(&connector->dev->mode_config.mutex);
- if (drm_add_modes_noedid(connector, 640, 480))
- drm_set_preferred_mode(connector, 640, 480);
- mutex_unlock(&connector->dev->mode_config.mutex);
- } else {
- /* always add fail-safe mode as backup mode */
- mutex_lock(&connector->dev->mode_config.mutex);
- drm_add_modes_noedid(connector, 640, 480);
- mutex_unlock(&connector->dev->mode_config.mutex);
+ dp_panel_add_fail_safe_mode(connector);
}
if (panel->aux_cfg_update_done) {
diff --git a/drivers/gpu/drm/msm/dp/dp_panel.h b/drivers/gpu/drm/msm/dp/dp_panel.h
index 9023e5b..99739ea 100644
--- a/drivers/gpu/drm/msm/dp/dp_panel.h
+++ b/drivers/gpu/drm/msm/dp/dp_panel.h
@@ -59,6 +59,7 @@ int dp_panel_init_panel_info(struct dp_panel *dp_panel);
int dp_panel_deinit(struct dp_panel *dp_panel);
int dp_panel_timing_cfg(struct dp_panel *dp_panel);
void dp_panel_dump_regs(struct dp_panel *dp_panel);
+void dp_panel_add_fail_safe_mode(struct drm_connector *connector);
int dp_panel_read_sink_caps(struct dp_panel *dp_panel,
struct drm_connector *connector);
u32 dp_panel_get_mode_bpp(struct dp_panel *dp_panel, u32 mode_max_bpp,
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
