[PATCH (repost) 3/5] drm_dp_mst_topology: fix broken drm_dp_sideband_parse_remote_dpcd_read()

[Lyude Paul]

On Mon, 2018-08-20 at 22:43 +0200, Hans Verkuil wrote:
> On 08/20/2018 08:59 PM, Lyude Paul wrote:
> > Reviewed-by: Lyude Paul <lyude at redhat.com>
> > 
> > We really need to add support for using this into the MST helpers. A good
> > way to
> > test this would probably be to hook up an aux device to the DP AUX adapters
> > we
> > create for each MST topology
> 
> If you are interested, I have code for that in my MST test branch:
> 
> https://git.linuxtv.org/hverkuil/media_tree.git/log/?h=cec-nv-amd-mst
> 
> It's the "drm_dp_mst_topology: use correct AUX channel" patch.
> 
> I don't have plans to post this patch since CEC for MST isn't working
> (still trying to figure out why not), but you are free to pick it up
> if you want.
Maybe someday but don't count on it yet! I've got a lot of stuff on my plate atm
:)

> 
> Regards,
> 
> 	Hans
> 
> > 
> > On Fri, 2018-08-17 at 16:11 +0200, Hans Verkuil wrote:
> > > From: Hans Verkuil <hans.verkuil at cisco.com>
> > > 
> > > When parsing the reply of a DP_REMOTE_DPCD_READ DPCD command the
> > > result is wrong due to a missing idx increment.
> > > 
> > > This was never noticed since DP_REMOTE_DPCD_READ is currently not
> > > used, but if you enable it, then it is all wrong.
> > > 
> > > Signed-off-by: Hans Verkuil <hans.verkuil at cisco.com>
> > > ---
> > >  drivers/gpu/drm/drm_dp_mst_topology.c | 1 +
> > >  1 file changed, 1 insertion(+)
> > > 
> > > diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c
> > > b/drivers/gpu/drm/drm_dp_mst_topology.c
> > > index 7780567aa669..5ff1d79b86c4 100644
> > > --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> > > +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> > > @@ -439,6 +439,7 @@ static bool
> > > drm_dp_sideband_parse_remote_dpcd_read(struct
> > > drm_dp_sideband_msg_rx
> > >  	if (idx > raw->curlen)
> > >  		goto fail_len;
> > >  	repmsg->u.remote_dpcd_read_ack.num_bytes = raw->msg[idx];
> > > +	idx++;
> > >  	if (idx > raw->curlen)
> > >  		goto fail_len;
> > >  
> 
>