[Intel-gfx] [PATCH 1/3] drm/display/dp_mst: Fix down/up message handling after sink disconnect

[Imre Deak]

On Fri, Dec 16, 2022 at 06:10:39PM +0200, Jani Nikula wrote:
> On Fri, 16 Dec 2022, Imre Deak <imre.deak at intel.com> wrote:
> > On Wed, Dec 14, 2022 at 04:41:42PM -0500, Lyude Paul wrote:
> >> For the whole series:
> >> 
> >> Reviewed-by: Lyude Paul <lyude at redhat.com>
> >
> > Thanks for the review, pushed it to drm-misc-next.
> 
> Hmm, with the drm-misc *not* cherry-picking patches from drm-misc-next
> to drm-misc-fixes, these will only get backported to stable kernels
> after they hit Linus' tree in the next (as opposed to current) merge
> window after a full development cycle. Wonder if they should be
> expedited.

Ok, it should've been pushed to -fixes then, will do that next time.
Yes, I think sending them already before the next merge window would be
good.

> 
> BR,
> Jani.
> 
> >
> >> Thanks!
> >> 
> >> On Wed, 2022-12-14 at 20:42 +0200, Imre Deak wrote:
> >> > If the sink gets disconnected during receiving a multi-packet DP MST AUX
> >> > down-reply/up-request sideband message, the state keeping track of which
> >> > packets have been received already is not reset. This results in a failed
> >> > sanity check for the subsequent message packet received after a sink is
> >> > reconnected (due to the pending message not yet completed with an
> >> > end-of-message-transfer packet), indicated by the
> >> > 
> >> > "sideband msg set header failed"
> >> > 
> >> > error.
> >> > 
> >> > Fix the above by resetting the up/down message reception state after a
> >> > disconnect event.
> >> > 
> >> > Cc: Lyude Paul <lyude at redhat.com>
> >> > Cc: <stable at vger.kernel.org> # v3.17+
> >> > Signed-off-by: Imre Deak <imre.deak at intel.com>
> >> > ---
> >> >  drivers/gpu/drm/display/drm_dp_mst_topology.c | 3 +++
> >> >  1 file changed, 3 insertions(+)
> >> > 
> >> > diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> >> > index 51a46689cda70..90819fff2c9ba 100644
> >> > --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
> >> > +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
> >> > @@ -3641,6 +3641,9 @@ int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool ms
> >> >  		drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL, 0);
> >> >  		ret = 0;
> >> >  		mgr->payload_id_table_cleared = false;
> >> > +
> >> > +		memset(&mgr->down_rep_recv, 0, sizeof(mgr->down_rep_recv));
> >> > +		memset(&mgr->up_req_recv, 0, sizeof(mgr->up_req_recv));
> >> >  	}
> >> >  
> >> >  out_unlock:
> >> 
> >> -- 
> >> Cheers,
> >>  Lyude Paul (she/her)
> >>  Software Engineer at Red Hat
> >> 
> 
> -- 
> Jani Nikula, Intel Open Source Graphics Center