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

[Jani Nikula <jani.nikula@linux.intel.com>]

On Fri, 16 Dec 2022, Imre Deak <imre.deak@intel.com> wrote:
> On Fri, Dec 16, 2022 at 06:10:39PM +0200, Jani Nikula wrote:
>> On Fri, 16 Dec 2022, Imre Deak <imre.deak@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@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.

Cc: drm-misc maintainers, I think this is for you to figure out.

BR,
Jani.


>
>> 
>> 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@redhat.com>
>> >> > Cc: <stable@vger.kernel.org> # v3.17+
>> >> > Signed-off-by: Imre Deak <imre.deak@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

-- 
Jani Nikula, Intel Open Source Graphics Center