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? > 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? > --- > 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]> > -- With best wishes Dmitry
