linux-kernel - RE: [PATCH v4 2/7] drm: rcar-du: lvds: Improve identification of panels

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Message-ID: <TY1PR01MB177010675ADC18D97DADADE8C0510@TY1PR01MB1770.jpnprd01.prod.outlook.com>
Date:   Mon, 16 Dec 2019 18:00:09 +0000
From:   Fabrizio Castro <fabrizio.castro@...renesas.com>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>
CC:     Geert Uytterhoeven <geert+renesas@...der.be>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Thierry Reding <thierry.reding@...il.com>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Sean Paul <sean@...rly.run>,
        Andrzej Hajda <a.hajda@...sung.com>,
        Sam Ravnborg <sam@...nborg.org>,
        Simon Horman <horms@...ge.net.au>,
        Magnus Damm <magnus.damm@...il.com>,
        Kieran Bingham <kieran.bingham+renesas@...asonboard.com>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-renesas-soc@...r.kernel.org" 
        <linux-renesas-soc@...r.kernel.org>,
        Chris Paterson <Chris.Paterson2@...esas.com>,
        Biju Das <biju.das@...renesas.com>,
        Jacopo Mondi <jacopo+renesas@...ndi.org>,
        "ebiharaml@...linux.co.jp" <ebiharaml@...linux.co.jp>
Subject: RE: [PATCH v4 2/7] drm: rcar-du: lvds: Improve identification of
 panels

Hi Laurent,

Thank you for your feedback!

> From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
> Sent: 13 December 2019 21:22
> Subject: Re: [PATCH v4 2/7] drm: rcar-du: lvds: Improve identification of panels
> 
> Hi Fabrizio,
> 
> Thank you for the patch.
> 
> On Fri, Dec 06, 2019 at 04:32:49PM +0000, Fabrizio Castro wrote:
> > Dual-LVDS panels are mistakenly identified as bridges, this
> > commit replaces the current logic with a call to
> > drm_of_find_panel_or_bridge to sort that out.
> >
> > Signed-off-by: Fabrizio Castro <fabrizio.castro@...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 | 45 +++++++++----------------------------
> >  1 file changed, 10 insertions(+), 35 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/rcar-du/rcar_lvds.c b/drivers/gpu/drm/rcar-du/rcar_lvds.c
> > index 8c6c172..3cb0a83 100644
> > --- a/drivers/gpu/drm/rcar-du/rcar_lvds.c
> > +++ b/drivers/gpu/drm/rcar-du/rcar_lvds.c
> > @@ -21,6 +21,7 @@
> >  #include <drm/drm_atomic.h>
> >  #include <drm/drm_atomic_helper.h>
> >  #include <drm/drm_bridge.h>
> > +#include <drm/drm_of.h>
> >  #include <drm/drm_panel.h>
> >  #include <drm/drm_probe_helper.h>
> >
> > @@ -705,10 +706,7 @@ static int rcar_lvds_parse_dt_companion(struct rcar_lvds *lvds)
> >  static int rcar_lvds_parse_dt(struct rcar_lvds *lvds)
> >  {
> >  	struct device_node *local_output = NULL;
> > -	struct device_node *remote_input = NULL;
> >  	struct device_node *remote = NULL;
> > -	struct device_node *node;
> > -	bool is_bridge = false;
> >  	int ret = 0;
> >
> >  	local_output = of_graph_get_endpoint_by_regs(lvds->dev->of_node, 1, 0);
> > @@ -736,45 +734,22 @@ static int rcar_lvds_parse_dt(struct rcar_lvds *lvds)
> >  		goto done;
> >  	}
> 
> I think you can remove the calls above this too.
> drm_of_find_panel_or_bridge() calls of_graph_get_remote_node(), which in
> turn calls of_graph_get_endpoint_by_regs(),
> of_graph_get_remote_port_parent() and checks the status of the remote
> with of_device_is_available().

Will take those out in v5

Thanks,
Fab

> 
> >
> > -	remote_input = of_graph_get_remote_endpoint(local_output);
> > -
> > -	for_each_endpoint_of_node(remote, node) {
> > -		if (node != remote_input) {
> > -			/*
> > -			 * We've found one endpoint other than the input, this
> > -			 * must be a bridge.
> > -			 */
> > -			is_bridge = true;
> > -			of_node_put(node);
> > -			break;
> > -		}
> > -	}
> > -
> > -	if (is_bridge) {
> > -		lvds->next_bridge = of_drm_find_bridge(remote);
> > -		if (!lvds->next_bridge) {
> > -			ret = -EPROBE_DEFER;
> > -			goto done;
> > -		}
> > +	ret = drm_of_find_panel_or_bridge(lvds->dev->of_node, 1, 0,
> > +					  &lvds->panel, &lvds->next_bridge);
> > +	if (ret)
> > +		goto done;
> >
> > -		if (lvds->info->quirks & RCAR_LVDS_QUIRK_DUAL_LINK)
> > -			lvds->dual_link = lvds->next_bridge->timings
> > -					? lvds->next_bridge->timings->dual_link
> > -					: false;
> > -	} else {
> > -		lvds->panel = of_drm_find_panel(remote);
> > -		if (IS_ERR(lvds->panel)) {
> > -			ret = PTR_ERR(lvds->panel);
> > -			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)
> >  		ret = rcar_lvds_parse_dt_companion(lvds);
> >
> >  done:
> >  	of_node_put(local_output);
> > -	of_node_put(remote_input);
> >  	of_node_put(remote);
> >
> >  	/*
> 
> --
> Regards,
> 
> Laurent Pinchart