RE: [PATCH v4 3/7] drm: rcar-du: lvds: Get dual link configuration from DT

[Fabrizio Castro <fabrizio.castro@bp.renesas.com>]

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