Re: [PATCH] drm/msm/dp: promote irq_hpd handle to handle link trainign correctly

[khsieh]

On 2020-11-02 11:29, Stephen Boyd wrote:
> Subject has a typo in "training".
>
> Quoting Kuogee Hsieh (2020-10-30 16:23:24)
> > Some dongles, such as Apple, required link training done at irq_hpd
>
> s/required/require/
>
> > request instead of plugin request. This patch promote irq_hpd hanlder
>
> s/hanlder/handler/
>
> > to handle link training and setup hpd_state correctly.
> >
> > Signed-off-by: Kuogee Hsieh <khsieh@xxxxxxxxxxxxxx>
> > ---
>
> Any Fixes tag?
>
> >  drivers/gpu/drm/msm/dp/dp_display.c | 20 ++++++++++++++++++--
> >  1 file changed, 18 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/msm/dp/dp_display.c 
> > b/drivers/gpu/drm/msm/dp/dp_display.c
> > index 13b66266cd69..55627530957c 100644
> > --- a/drivers/gpu/drm/msm/dp/dp_display.c
> > +++ b/drivers/gpu/drm/msm/dp/dp_display.c
> > @@ -483,10 +485,24 @@ static int dp_display_usbpd_attention_cb(struct 
> > device *dev)
> >                 return -ENODEV;
> >         }
> >
> > +       hpd = dp->usbpd;
> > +
> >         /* check for any test request issued by sink */
> >         rc = dp_link_process_request(dp->link);
> > -       if (!rc)
> > -               dp_display_handle_irq_hpd(dp);
> > +       if (!rc) {
> > +               sink_request = dp->link->sink_request;
> > +               if (sink_request & DS_PORT_STATUS_CHANGED) {
> > +                       dp->hpd_state = ST_CONNECT_PENDING;
> > +                       hpd->hpd_high = 1;
> > +               }
> > +
> > +               rc = dp_display_handle_irq_hpd(dp);
> > +
> > +               if (rc && sink_request & DS_PORT_STATUS_CHANGED) {
>
> Can you add parenthesis around this?
>
> 		if (rc && (sink_request & DS_PORT_STATUS_CHANGED)) {
>
>
> I honestly don't know what's going on in this patch. It talks about
> making link training happen during irq hpd handler but this is the
> attention handler and we're checking port status changed? This is
> related? The code is really not clear.
irq_hpd request is generated by sinker to ask host attention that 
something has changed.
POST_STATUS_CHNAGED bit set  by sinker to indicated link had loss of 
sync. Therefore
host need to restart link retaining to fix the link loss of sync 
problem.

> > +                       hpd->hpd_high = 0;
> > +                       dp->hpd_state = ST_DISCONNECTED;
> > +               }
> > +       }
> >
> >         return rc;
> >  }
> >
> > base-commit: 0e162b10644605428cd2596c12f8ed410cf9d2d9
>
> What commit is this?