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SubjectRE: [PATCH v4 3/7] drm: rcar-du: lvds: Get dual link configuration from DT
Date
Hi Laurent,

Thank you for your feedback!

> From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Sent: 13 December 2019 21:30
> Subject: Re: [PATCH v4 3/7] drm: rcar-du: lvds: Get dual link configuration from DT
>
> Hi Fabrizio,
>
> Thank you for the patch.
>
> On Fri, Dec 06, 2019 at 04:32:50PM +0000, Fabrizio Castro wrote:
> > For dual-LVDS configurations, it is now possible to mark the
> > DT port nodes for the sink with boolean properties (like
> > dual-lvds-even-pixels and dual-lvds-odd-pixels) to let drivers
> > know the encoders need to be configured in dual-LVDS mode.
> >
> > Rework the implementation of rcar_lvds_parse_dt_companion
> > to make use of the DT markers while keeping backward
> > compatibility.
> >
> > Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
> >
> > ---
> > v3->v4:
> > * New patch extracted from patch:
> > "drm: rcar-du: lvds: Add dual-LVDS panels support"
> > ---
> > drivers/gpu/drm/rcar-du/rcar_lvds.c | 56 +++++++++++++++++++++++++++++++------
> > 1 file changed, 47 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/rcar-du/rcar_lvds.c b/drivers/gpu/drm/rcar-du/rcar_lvds.c
> > index 3cb0a83..6c1f171 100644
> > --- a/drivers/gpu/drm/rcar-du/rcar_lvds.c
> > +++ b/drivers/gpu/drm/rcar-du/rcar_lvds.c
> > @@ -669,8 +669,10 @@ EXPORT_SYMBOL_GPL(rcar_lvds_dual_link);
> > static int rcar_lvds_parse_dt_companion(struct rcar_lvds *lvds)
> > {
> > const struct of_device_id *match;
> > - struct device_node *companion;
> > + struct device_node *companion, *p0, *p1;
>
> Could you rename p0 and p1 to port0 and port1, and spit them to a
> separate line of variable declaration ?

sure

>
> > + struct rcar_lvds *companion_lvds;
> > struct device *dev = lvds->dev;
> > + int dual_link;
> > int ret = 0;
> >
> > /* Locate the companion LVDS encoder for dual-link operation, if any. */
> > @@ -689,13 +691,55 @@ static int rcar_lvds_parse_dt_companion(struct rcar_lvds *lvds)
> > goto done;
> > }
> >
> > + /*
> > + * We need to work out if the sink is expecting us to function in
> > + * dual-link mode. We do this by looking at the DT port nodes we are
> > + * connected to, if they are marked as expecting even pixels and
> > + * odd pixels than we need to enable vertical stripe output.
> > + */
> > + p0 = of_graph_get_port_by_id(dev->of_node, 1);
> > + p1 = of_graph_get_port_by_id(companion, 1);
> > + dual_link = drm_of_lvds_get_dual_link_pixel_order(p0, p1);
> > + of_node_put(p0);
> > + of_node_put(p1);
> > + if (dual_link >= DRM_LVDS_DUAL_LINK_EVEN_ODD_PIXELS) {
> > + lvds->dual_link = true;
> > + } else if (lvds->next_bridge && lvds->next_bridge->timings) {
> > + /*
> > + * Early dual-link bridge specific implementations populate the
> > + * timings field of drm_bridge, read the dual_link flag off the
> > + * bridge directly for backward compatibility.
> > + */
> > + lvds->dual_link = lvds->next_bridge->timings->dual_link;
> > + }
> > +
> > + if (!lvds->dual_link) {
> > + dev_dbg(dev, "Single-link configuration detected\n");
> > + goto done;
> > + }
> > +
> > lvds->companion = of_drm_find_bridge(companion);
> > if (!lvds->companion) {
> > ret = -EPROBE_DEFER;
> > goto done;
> > }
> >
> > - dev_dbg(dev, "Found companion encoder %pOF\n", companion);
> > + dev_dbg(dev,
> > + "Dual-link configuration detected (companion encoder %pOF)\n",
> > + companion);
> > +
> > + companion_lvds = bridge_to_rcar_lvds(lvds->companion);
>
> Could you move this line after the FIXME comment ?

Will do

Thanks,
Fab

>
> With these small issues fixed,
>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
>
> > +
> > + /*
> > + * FIXME: We should not be messing with the companion encoder private
> > + * data from the primary encoder, we should rather let the companion
> > + * encoder work things out on its own. However, the companion encoder
> > + * doesn't hold a reference to the primary encoder, and
> > + * drm_of_lvds_get_dual_link_pixel_order needs to be given references
> > + * to the output ports of both encoders, therefore leave it like this
> > + * for the time being.
> > + */
> > + companion_lvds->dual_link = true;
> >
> > done:
> > of_node_put(companion);
> > @@ -739,13 +783,7 @@ static int rcar_lvds_parse_dt(struct rcar_lvds *lvds)
> > if (ret)
> > goto done;
> >
> > - if ((lvds->info->quirks & RCAR_LVDS_QUIRK_DUAL_LINK) &&
> > - lvds->next_bridge)
> > - lvds->dual_link = lvds->next_bridge->timings
> > - ? lvds->next_bridge->timings->dual_link
> > - : false;
> > -
> > - if (lvds->dual_link)
> > + if (lvds->info->quirks & RCAR_LVDS_QUIRK_DUAL_LINK)
> > ret = rcar_lvds_parse_dt_companion(lvds);
> >
> > done:
>
> --
> Regards,
>
> Laurent Pinchart
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