On 5/13/2026 9:28 PM, Dmitry Baryshkov wrote:
On Mon, May 11, 2026 at 04:36:03PM +0800, Yongxing Mou wrote:
On eDP interfaces with no panel connected, panel-simple-dp-aux fails to
read DPCD over AUX during probe, leaving hpd_state at ST_DISCONNECTED.
msm_dp_bridge_atomic_enable() exits early as a result, so
Why is atomic_enable() called for disconnected bridge?
Sorry, I wasn't very clear. What I meant is that the hpd_state is
ST_DISCONNECTED when no eDP panel is connected. However, the eDP
connector is always reported as connected because it does not implement
a .detect() callback and assumes that the panel is always present.
msm_dp_display_enable() is never called and power_on remains false with
link clocks never enabled.
During system suspend, drm_atomic_helper_suspend() still invokes
atomic_disable() for all registered bridges. The resulting write to
REG_DP_STATE_CTRL against an unpowered controller triggers a NoC slave
error, causing a fatal crash.
Guard push_idle with a power_on check to skip the register access when the
display was never enabled.
Signed-off-by: Yongxing Mou <[email protected]>
Fixes?
Got it.
---
drivers/gpu/drm/msm/dp/dp_display.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/drivers/gpu/drm/msm/dp/dp_display.c
b/drivers/gpu/drm/msm/dp/dp_display.c
index 1b3cbf4016ef..51b60eb9c2df 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -1660,6 +1660,13 @@ void msm_dp_bridge_atomic_disable(struct drm_bridge
*drm_bridge,
msm_dp_display = container_of(dp, struct msm_dp_display_private, msm_dp_display);
+ /*
+ * push_idle accesses link registers which require link clocks to be on.
+ * Skip if the display was never powered on (e.g. eDP with no panel).
+ */
+ if (!dp->power_on)
+ return;
+
msm_dp_ctrl_push_idle(msm_dp_display->ctrl);
}
---
base-commit: e98d21c170b01ddef366f023bbfcf6b31509fa83
change-id: 20260511-edp_suspend-0e45d0110633
Best regards,
--
Yongxing Mou <[email protected]>
