[PATCH 10/14] drm/bridge: analogix_dp: move macro reset after link bandwidth setting

[Robert Foss]

On Tue, May 7, 2024 at 3:07 PM Robert Foss <rfoss at kernel.org> wrote:
>
> On Fri, May 3, 2024 at 5:13 PM Lucas Stach <l.stach at pengutronix.de> wrote:
> >
> > Setting the link bandwidth may change the PLL parameters, which will cause
> > the PLL to go out of lock, so make sure to apply the MACRO_RST, which
> > according to the comment is required to be pulsed after the PLL is locked.
> >
> > Signed-off-by: Lucas Stach <l.stach at pengutronix.de>
> > ---
> >  .../gpu/drm/bridge/analogix/analogix_dp_core.c | 18 ++++++++++--------
> >  1 file changed, 10 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> > index b4a47311cfe8..736b2ed745e1 100644
> > --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> > +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
> > @@ -243,6 +243,11 @@ static int analogix_dp_link_start(struct analogix_dp_device *dp)
> >
> >         /* Set link rate and count as you want to establish*/
> >         analogix_dp_set_link_bandwidth(dp, dp->link_train.link_rate);
> > +       /*
> > +        * MACRO_RST must be applied after the PLL_LOCK to avoid
> > +        * the DP inter pair skew issue for at least 10 us
> > +        */
> > +       analogix_dp_reset_macro(dp);
> >         analogix_dp_set_lane_count(dp, dp->link_train.lane_count);
> >
> >         /* Setup RX configuration */
> > @@ -565,12 +570,6 @@ static int analogix_dp_full_link_train(struct analogix_dp_device *dp,
> >         int retval = 0;
> >         bool training_finished = false;
> >
> > -       /*
> > -        * MACRO_RST must be applied after the PLL_LOCK to avoid
> > -        * the DP inter pair skew issue for at least 10 us
> > -        */
> > -       analogix_dp_reset_macro(dp);
> > -
> >         /* Initialize by reading RX's DPCD */
> >         analogix_dp_get_max_rx_bandwidth(dp, &dp->link_train.link_rate);
> >         analogix_dp_get_max_rx_lane_count(dp, &dp->link_train.lane_count);
> > @@ -637,9 +636,12 @@ static int analogix_dp_fast_link_train(struct analogix_dp_device *dp)
> >         u8 link_align, link_status[2];
> >         enum pll_status status;
> >
> > -       analogix_dp_reset_macro(dp);
> > -
> >         analogix_dp_set_link_bandwidth(dp, dp->link_train.link_rate);
> > +       /*
> > +        * MACRO_RST must be applied after the PLL_LOCK to avoid
> > +        * the DP inter pair skew issue for at least 10 us
> > +        */
> > +       analogix_dp_reset_macro(dp);
> >         analogix_dp_set_lane_count(dp, dp->link_train.lane_count);
> >         analogix_dp_set_lane_link_training(dp);
> >
> > --
> > 2.39.2
> >
>
> This patch does not apply on drm-misc/drm-misc-next as far as I can tell.

Reviewed-by: Robert Foss <rfoss at kernel.org>