[Intel-gfx] [PATCH] drm/i915/hdcp: Remove drm_modeset_lock in intel_conn_to_vcpi

[Kandpal, Suraj]

> 
> On Thu, Mar 16, 2023 at 01:52:32PM +0530, Suraj Kandpal wrote:
> > Remove drm_modeset_lock in intel_conn_to_vcpi as we don't need it
> > anymore since all the required locks are taken in atomic check and
> > prepare phases.
> >
> > Signed-off-by: Suraj Kandpal <suraj.kandpal at intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_hdcp.c | 2 --
> >  1 file changed, 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_hdcp.c
> > b/drivers/gpu/drm/i915/display/intel_hdcp.c
> > index 2984d2810e42..f957b4bd9c26 100644
> > --- a/drivers/gpu/drm/i915/display/intel_hdcp.c
> > +++ b/drivers/gpu/drm/i915/display/intel_hdcp.c
> > @@ -41,7 +41,6 @@ static int intel_conn_to_vcpi(struct intel_connector
> *connector)
> >  		return 0;
> >  	mgr = connector->port->mgr;
> >
> > -	drm_modeset_lock(&mgr->base.lock, NULL);
> >  	mst_state = to_drm_dp_mst_topology_state(mgr->base.state);
> >  	payload = drm_atomic_get_mst_payload_state(mst_state,
> connector->port);
> >  	if (drm_WARN_ON(mgr->dev, !payload)) @@ -53,7 +52,6 @@ static
> int
> > intel_conn_to_vcpi(struct intel_connector *connector)
> >  		goto out;
> >  	}
> >  out:
> > -	drm_modeset_unlock(&mgr->base.lock);
> >  	return vcpi;
> >  }
> 
> That whole function looks like it something that should be part of the
> drm_dp_mst_helper.c.
> 
> Also, it's directly accessing mgr->base.state which is just wrong.
> 
> And it looks like it can get called from outside the normal atomic commit
> flows (like so many other things in the hdcp code, sigh), so what you're doing
> here is also wrong in that case.
> 

Okay but as of now we are seeing a lock error which does not allow us to enable
HDCP (VLK-45132) when DPMST is connected so how do I move forward in a way that solves the
Issue and we access mgr->base.state in an acceptable manner

Regards,
Suraj Kandpal
> So the whole thing looks just very broken to me. Not to mention the HDCP vs.
> MST<->SST switch is also still fundementally broken. I'm really tempted to
> just send a patch to nuke the entire HDCP MST code.
> 
> --
> Ville Syrjälä
> Intel