> -----Original Message-----
> From: Lyude Paul <lyude@xxxxxxxxxx>
> Sent: Tuesday, December 3, 2019 8:23 AM
> To: Lin, Wayne <Wayne.Lin@xxxxxxx>; dri-devel@xxxxxxxxxxxxxxxxxxxxx;
> amd-gfx@xxxxxxxxxxxxxxxxxxxxx
> Cc: Kazlauskas, Nicholas <Nicholas.Kazlauskas@xxxxxxx>; Wentland, Harry
> <Harry.Wentland@xxxxxxx>; Zuo, Jerry <Jerry.Zuo@xxxxxxx>
> Subject: Re: [PATCH] drm/dp_mst: Correct the bug in
> drm_dp_update_payload_part1()
>
> On Mon, 2019-12-02 at 11:58 +0800, Wayne Lin wrote:
> > [Why]
> > If the payload_state is DP_PAYLOAD_DELETE_LOCAL in series, current
> > code doesn't delete the payload at current index and just move the
> > index to next one after shuffling payloads.
> >
> > [How]
> > After shuffling payloads, decide whether to move on index or not
> > according to payload_state of current payload.
> >
> > Signed-off-by: Wayne Lin <Wayne.Lin@xxxxxxx>
> > ---
> > drivers/gpu/drm/drm_dp_mst_topology.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c
> > b/drivers/gpu/drm/drm_dp_mst_topology.c
> > index 81e92b260d7a..8da5d461ea01 100644
> > --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> > +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> > @@ -3176,7 +3176,8 @@ int drm_dp_update_payload_part1(struct
> > drm_dp_mst_topology_mgr *mgr)
> > drm_dp_mst_topology_put_port(port);
> > }
> >
> > - for (i = 0; i < mgr->max_payloads; i++) {
> > + for (i = 0; i < mgr->max_payloads;
> > + (mgr->payloads[i].payload_state == DP_PAYLOAD_DELETE_LOCAL) ?
> > i : i++) {
>
> Took me a moment to figure out what this line was actually doing. Nice catch
> by the way!
>
> Anyway: let's just drop this line to avoid making things confusing to read, drop
> i++ from the for loop instead, and just rewrite it so it looks like this:
>
> for (i = 0; i < mgr->max_payloads; /* do nothing */) {
> if (mgr->payloads[i].payload_state != DP_PAYLOAD_DELETE_LOCAL) {
> i++;
> continue;
> }
>
> With those changes, this patch is:
>
> Reviewed-by: Lyude Paul <lyude@xxxxxxxxxx>
>
Thanks for your time and sorry for not well organized code.
I will send you the v2 right away. Thanks!
> I can go ahead and push these patches to drm-misc for you once you've sent
> me the v2
> > if (mgr->payloads[i].payload_state != DP_PAYLOAD_DELETE_LOCAL)
> > continue;
> >
> --
> Cheers,
> Lyude Paul
--
BR,
Wayne Lin
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