Re: [PATCH] drm/msm/dp: Skip push_idle in atomic_disable if display is not powered on

[Yongxing Mou]

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 <yongxing.mou@xxxxxxxxxxxxxxxx>
>
> 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 <yongxing.mou@xxxxxxxxxxxxxxxx>