Re: [PATCH v3] drm/dp_mst: Fix return code on sideband message failure

[khsieh]

On 2021-07-22 10:53, Lyude Paul wrote:
> On Tue, 2021-07-13 at 15:24 -0700, khsieh@xxxxxxxxxxxxxx wrote:
> > On 2021-07-07 01:37, Jani Nikula wrote:
> > > On Tue, 06 Jul 2021, Kuogee Hsieh <khsieh@xxxxxxxxxxxxxx> wrote:
> > > > From: Rajkumar Subbiah <rsubbia@xxxxxxxxxxxxxx>
> > > >
> > > > Commit 2f015ec6eab6 ("drm/dp_mst: Add sideband down request tracing +
> > > > selftests") added some debug code for sideband message tracing. But
> > > > it seems to have unintentionally changed the behavior on sideband
> > > > message
> > > > failure. It catches and returns failure only if DRM_UT_DP is enabled.
> > > > Otherwise it ignores the error code and returns success. So on an MST
> > > > unplug, the caller is unaware that the clear payload message failed
> > > > and
> > > > ends up waiting for 4 seconds for the response. Fixes the issue by
> > > > returning the proper error code.
> > > >
> > > > Changes in V2:
> > > > -- Revise commit text as review comment
> > > > -- add Fixes text
> > > >
> > > > Changes in V3:
> > > > -- remove "unlikely" optimization
> > > >
> > > > Fixes: 2f015ec6eab6 ("drm/dp_mst: Add sideband down request tracing +
> > > > selftests")
> > > >
> > > > Signed-off-by: Rajkumar Subbiah <rsubbia@xxxxxxxxxxxxxx>
> > > > Signed-off-by: Kuogee Hsieh <khsieh@xxxxxxxxxxxxxx>
> > > >
> > > > Reviewed-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
> > >
> > > Reviewed-by: Jani Nikula <jani.nikula@xxxxxxxxx>
> > >
> > >
> > > > ---
> > Lyude,
> > Any comments from you?
> > Thanks,
>
> Hey! Sorry did I forget to respond to this?
>
> Reviewed-by: Lyude Paul <lyude@xxxxxxxxxx>

It looks like this patch is good to go (mainlined).
Anything needed from me to do?
Thanks,

> > > >  drivers/gpu/drm/drm_dp_mst_topology.c | 10 ++++++----
> > > >  1 file changed, 6 insertions(+), 4 deletions(-)
> > > >
> > > > diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c
> > > > b/drivers/gpu/drm/drm_dp_mst_topology.c
> > > > index 1590144..df91110 100644
> > > > --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> > > > +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> > > > @@ -2887,11 +2887,13 @@ static int process_single_tx_qlock(struct
> > > > drm_dp_mst_topology_mgr *mgr,
> > > >         idx += tosend + 1;
> > > >
> > > >         ret = drm_dp_send_sideband_msg(mgr, up, chunk, idx);
> > > > -       if (unlikely(ret) && drm_debug_enabled(DRM_UT_DP)) {
> > > > -               struct drm_printer p = drm_debug_printer(DBG_PREFIX);
> > > > +       if (ret) {
> > > > +               if (drm_debug_enabled(DRM_UT_DP)) {
> > > > +                       struct drm_printer p =
> > > > drm_debug_printer(DBG_PREFIX);
> > > >
> > > > -               drm_printf(&p, "sideband msg failed to send\n");
> > > > -               drm_dp_mst_dump_sideband_msg_tx(&p, txmsg);
> > > > +                       drm_printf(&p, "sideband msg failed to send\n");
> > > > +                       drm_dp_mst_dump_sideband_msg_tx(&p, txmsg);
> > > > +               }
> > > >                 return ret;
> > > >         }