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From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Sam Ravnborg <sam@ravnborg.org>
Cc: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>,
	Liu Ying <victor.liu@nxp.com>,
	dri-devel@lists.freedesktop.org,
	Marcel Ziswiler <marcel.ziswiler@toradex.com>,
	Pascal Roeleven <dev@pascalroeleven.nl>,
	Thierry Reding <thierry.reding@gmail.com>,
	Dmitry Osipenko <digetx@gmail.com>
Subject: Re: [PATCH] drm: panel: simple: Drop drive/sample bus flags for LVDS panels
Date: Sun, 28 Jun 2020 14:48:20 +0300	[thread overview]
Message-ID: <20200628114820.GO6954@pendragon.ideasonboard.com> (raw)
In-Reply-To: <20200628091347.GA133729@ravnborg.org>

Hi Sam,

On Sun, Jun 28, 2020 at 11:13:47AM +0200, Sam Ravnborg wrote:
> On Sun, Jun 28, 2020 at 10:54:01AM +0300, Laurent Pinchart wrote:
> > The DRM bus flags reporting on which clock edge the pixel data and sync
> > signals are sampled or driven don't make sense for LVDS panels, as the
> > bus then uses sub-clock timings to send data. Drop those flags and add a
> > warning in the probe function to make sure the mistake won't be
> > repeated.
> > 
> > Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
> > ---
> >  drivers/gpu/drm/panel/panel-simple.c | 30 +++++++++++++++++-----------
> >  1 file changed, 18 insertions(+), 12 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
> > index bff1cab529d2..537d75ef7fc2 100644
> > --- a/drivers/gpu/drm/panel/panel-simple.c
> > +++ b/drivers/gpu/drm/panel/panel-simple.c
> > @@ -549,6 +549,14 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)
> >  			panel_simple_parse_panel_timing_node(dev, panel, &dt);
> >  	}
> >  
> > +	if (desc->connector_type == DRM_MODE_CONNECTOR_LVDS)
> > +		/* Catch common mistakes for LVDS panels. */
> > +		WARN_ON(desc->bus_flags &
> > +			(DRM_BUS_FLAG_PIXDATA_POSEDGE |
> > +			 DRM_BUS_FLAG_PIXDATA_NEGEDGE |
> > +			 DRM_BUS_FLAG_SYNC_POSEDGE |
> > +			 DRM_BUS_FLAG_SYNC_NEGEDGE));
>
> The above are only the legacy flags.

We currently have

	DRM_BUS_FLAG_PIXDATA_POSEDGE = BIT(2),
	DRM_BUS_FLAG_PIXDATA_NEGEDGE = BIT(3),
	DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE = DRM_BUS_FLAG_PIXDATA_POSEDGE,
	DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE = DRM_BUS_FLAG_PIXDATA_NEGEDGE,
	DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE = DRM_BUS_FLAG_PIXDATA_NEGEDGE,
	DRM_BUS_FLAG_PIXDATA_SAMPLE_NEGEDGE = DRM_BUS_FLAG_PIXDATA_POSEDGE,

Only the first two are legacy, but the last four have the same values. I
could pick DRIVE or SAMPLE (the latter seems to be a better match here)
instead.

> For LVDS panels I think we could check if either
> DRM_BUS_FLAG_DE_LOW or DRM_BUS_FLAG_DE_HIGH is set and nothing else.

A whitelist instead of a blacklist is a good idea.

> And then as an additional check that the .bus_format is relevant.

I have a patch for that, but we first need to fix two occurrences of
incorrect formats. As I couldn't find documentation for these two
panels, I've replied to the patches that introduced them, and am waiting
for answers.

> Then we have managed to catch most of the mistakes for LVDS panels.
> 
> We could add checks for DPI panels too, but that would be later.
> 
> > +
> >  	drm_panel_init(&panel->base, dev, &panel_simple_funcs,
> >  		       desc->connector_type);
> >  
> > @@ -688,7 +696,7 @@ static const struct panel_desc auo_b101aw03 = {
> >  		.height = 125,
> >  	},
> >  	.bus_format = MEDIA_BUS_FMT_RGB666_1X7X3_SPWG,
> > -	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
> > +	.bus_flags = DRM_BUS_FLAG_DE_HIGH,
> >  	.connector_type = DRM_MODE_CONNECTOR_LVDS,
> >  };
> >  
> > @@ -1398,7 +1406,7 @@ static const struct panel_desc chunghwa_claa070wp03xg = {
> >  		.height = 150,
> >  	},
> >  	.bus_format = MEDIA_BUS_FMT_RGB666_1X7X3_SPWG,
> > -	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
> > +	.bus_flags = DRM_BUS_FLAG_DE_HIGH,
> >  	.connector_type = DRM_MODE_CONNECTOR_LVDS,
> >  };
> >  
> > @@ -1423,7 +1431,7 @@ static const struct panel_desc chunghwa_claa101wa01a = {
> >  		.height = 120,
> >  	},
> >  	.bus_format = MEDIA_BUS_FMT_RGB666_1X7X3_SPWG,
> > -	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
> > +	.bus_flags = DRM_BUS_FLAG_DE_HIGH,
> >  	.connector_type = DRM_MODE_CONNECTOR_LVDS,
> >  };
> >  
> > @@ -1448,7 +1456,7 @@ static const struct panel_desc chunghwa_claa101wb01 = {
> >  		.height = 125,
> >  	},
> >  	.bus_format = MEDIA_BUS_FMT_RGB666_1X7X3_SPWG,
> > -	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
> > +	.bus_flags = DRM_BUS_FLAG_DE_HIGH,
> >  	.connector_type = DRM_MODE_CONNECTOR_LVDS,
> >  };
> >  
> > @@ -2123,7 +2131,7 @@ static const struct panel_desc innolux_n156bge_l21 = {
> >  		.height = 193,
> >  	},
> >  	.bus_format = MEDIA_BUS_FMT_RGB666_1X7X3_SPWG,
> > -	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
> > +	.bus_flags = DRM_BUS_FLAG_DE_HIGH,
> >  	.connector_type = DRM_MODE_CONNECTOR_LVDS,
> >  };
> >  
> > @@ -2256,7 +2264,7 @@ static const struct panel_desc koe_tx26d202vm0bwa = {
> >  		.disable = 1000,
> >  	},
> >  	.bus_format = MEDIA_BUS_FMT_RGB888_1X7X4_SPWG,
> > -	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
> > +	.bus_flags = DRM_BUS_FLAG_DE_HIGH,
> >  	.connector_type = DRM_MODE_CONNECTOR_LVDS,
> >  };
> >  
> > @@ -2497,9 +2505,7 @@ static const struct panel_desc logictechno_lt170410_2whc = {
> >  		.height = 136,
> >  	},
> >  	.bus_format = MEDIA_BUS_FMT_RGB888_1X7X4_SPWG,
> > -	.bus_flags = DRM_BUS_FLAG_DE_HIGH |
> > -		     DRM_BUS_FLAG_PIXDATA_SAMPLE_NEGEDGE |
> > -		     DRM_BUS_FLAG_SYNC_SAMPLE_NEGEDGE,
> > +	.bus_flags = DRM_BUS_FLAG_DE_HIGH,
> >  	.connector_type = DRM_MODE_CONNECTOR_LVDS,
> >  };
> >  
> > @@ -3072,7 +3078,7 @@ static const struct panel_desc samsung_ltn101nt05 = {
> >  		.height = 125,
> >  	},
> >  	.bus_format = MEDIA_BUS_FMT_RGB666_1X7X3_SPWG,
> > -	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
> > +	.bus_flags = DRM_BUS_FLAG_DE_HIGH,
> >  	.connector_type = DRM_MODE_CONNECTOR_LVDS,
> >  };
> >  
> > @@ -3319,7 +3325,7 @@ static const struct panel_desc starry_kr070pe2t = {
> >  		.height = 86,
> >  	},
> >  	.bus_format = MEDIA_BUS_FMT_RGB888_1X24,
> > -	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE,
> > +	.bus_flags = DRM_BUS_FLAG_DE_HIGH,
> >  	.connector_type = DRM_MODE_CONNECTOR_LVDS,
> >  };
> >  
> > @@ -3512,7 +3518,7 @@ static const struct panel_desc toshiba_lt089ac29000 = {
> >  		.height = 116,
> >  	},
> >  	.bus_format = MEDIA_BUS_FMT_RGB888_1X7X4_JEIDA,
> > -	.bus_flags = DRM_BUS_FLAG_DE_HIGH | DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
> > +	.bus_flags = DRM_BUS_FLAG_DE_HIGH,
> >  	.connector_type = DRM_MODE_CONNECTOR_LVDS,
> >  };
> >  

-- 
Regards,

Laurent Pinchart
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dri-devel@lists.freedesktop.org
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  reply	other threads:[~2020-06-28 11:48 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-28  7:54 [PATCH] drm: panel: simple: Drop drive/sample bus flags for LVDS panels Laurent Pinchart
2020-06-28  9:13 ` Sam Ravnborg
2020-06-28 11:48   ` Laurent Pinchart [this message]
2020-06-28 17:29     ` Sam Ravnborg
2020-06-29  4:43 ` Dmitry Osipenko

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