Re: [PATCH 3/7] drm/msm/dp: reset aux controller after dp_aux_cmd_fifo_tx() failed.

[khsieh]

On 2021-07-08 00:34, Stephen Boyd wrote:
> Quoting Kuogee Hsieh (2021-07-06 10:20:16)
> > Aux hardware calibration sequence requires resetting the aux 
> > controller
> > in order for the new setting to take effect. However resetting the AUX
> > controller will also clear HPD interrupt status which may accidentally
> > cause pending unplug interrupt to get lost. Therefore reset aux
> > controller only when link is in connection state when 
> > dp_aux_cmd_fifo_tx()
> > fail. This fixes Link Layer CTS cases 4.2.1.1 and 4.2.1.2.
> >
> > Signed-off-by: Kuogee Hsieh <khsieh@xxxxxxxxxxxxxx>
> > ---
> >  drivers/gpu/drm/msm/dp/dp_aux.c | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/msm/dp/dp_aux.c 
> > b/drivers/gpu/drm/msm/dp/dp_aux.c
> > index 4a3293b..eb40d84 100644
> > --- a/drivers/gpu/drm/msm/dp/dp_aux.c
> > +++ b/drivers/gpu/drm/msm/dp/dp_aux.c
> > @@ -353,6 +353,9 @@ static ssize_t dp_aux_transfer(struct drm_dp_aux 
> > *dp_aux,
> >                         if (!(aux->retry_cnt % MAX_AUX_RETRIES))
> >                                 
> > dp_catalog_aux_update_cfg(aux->catalog);
> >                 }
> > +               /* reset aux if link is in connected state */
> > +               if (dp_catalog_link_is_connected(aux->catalog))
>
> How do we avoid resetting aux when hpd is unplugged and then plugged
> back in during an aux transfer?
i am not sure this is possible.
it should get unplug interrupt followed by plugin interrupt.
In this case, aux will be re set and initialized
> > +                       dp_catalog_aux_reset(aux->catalog);
> >         } else {
> >                 aux->retry_cnt = 0;
> >                 switch (aux->aux_error_num) {
> > --
> > The Qualcomm Innovation Center, Inc. is a member of the Code Aurora 
> > Forum,
> > a Linux Foundation Collaborative Project