JFYI this is on my radar and I'll take a look asap
On Tue, 2021-06-29 at 13:41 -0700, Stephen Boyd wrote:
> +Lyude, author of fixed commit. Please add relevant folks in the future.
>
> Quoting Kuogee Hsieh (2021-06-29 13:08:56)
> > From: Rajkumar Subbiah <rsubbia@xxxxxxxxxxxxxx>
> >
> > The commit 2f015ec6eab69301fdcf54d397810d72362d7223 added some debug
>
> Please write
>
> 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.
> >
> > This change fixes the issue by returning the proper error code.
>
> $ git grep "This patch" -- Documentation/process
>
> >
> > Change-Id: I2887b7ca21355fe84a7968f7619d5e8199cbb0c6
>
> Please replace with
>
> Fixes: 2f015ec6eab6 ("drm/dp_mst: Add sideband down request tracing +
> selftests")
>
> > Signed-off-by: Rajkumar Subbiah <rsubbia@xxxxxxxxxxxxxx>
>
> Should be a Signed-off-by from Kuogee Hsieh here.
>
> > ---
> > 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..8d97430 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 (unlikely(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;
> > }
> >
>
> With the above fixed up
>
> Reviewed-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
>
--
Cheers,
Lyude Paul (she/her)
Software Engineer at Red Hat
