Re: [RFC PATCH] drm/panel: simple: panel-dpi: use bus-format to set bpc and bus_format

From: Maxime Ripard <maxime@cerno.tech>
To: Marek Vasut <marex@denx.de>
Cc: Christoph Niedermaier <cniedermaier@dh-electronics.com>,
	Max Krummenacher <max.krummenacher@toradex.com>,
	Pengutronix Kernel Team <kernel@pengutronix.de>,
	Max Krummenacher <max.oss.09@gmail.com>,
	David Airlie <airlied@linux.ie>, Sam Ravnborg <sam@ravnborg.org>,
	Sascha Hauer <s.hauer@pengutronix.de>,
	dri-devel@lists.freedesktop.org,
	DenysDrozdov <denys.drozdov@toradex.com>,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	Shawn Guo <shawnguo@kernel.org>,
	linux-arm-kernel@lists.infradead.org,
	NXP Linux Team <linux-imx@nxp.com>
Subject: Re: [RFC PATCH] drm/panel: simple: panel-dpi: use bus-format to set bpc and bus_format
Date: Wed, 23 Feb 2022 14:47:57 +0100	[thread overview]
Message-ID: <20220223134757.f5upi2iun27op5w5@houat> (raw)
In-Reply-To: <b5f471f4-0712-b798-efb8-b5b481cdb898@denx.de>

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On Wed, Feb 23, 2022 at 02:45:30PM +0100, Marek Vasut wrote:
> On 2/23/22 14:41, Maxime Ripard wrote:
> > Hi,
> > 
> > On Tue, Feb 22, 2022 at 09:47:23AM +0100, Max Krummenacher wrote:
> > > Use the new property bus-format to set the enum bus_format and bpc.
> > > Completes: commit 4a1d0dbc8332 ("drm/panel: simple: add panel-dpi support")
> > > 
> > > Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>
> > > 
> > > ---
> > > 
> > >   drivers/gpu/drm/panel/panel-simple.c | 32 ++++++++++++++++++++++++++++
> > >   1 file changed, 32 insertions(+)
> > > 
> > > Relates to the discussion: https://lore.kernel.org/all/20220201110717.3585-1-cniedermaier@dh-electronics.com/
> > > 
> > > Max
> > > 
> > > diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
> > > index c5f133667a2d..5c07260de71c 100644
> > > --- a/drivers/gpu/drm/panel/panel-simple.c
> > > +++ b/drivers/gpu/drm/panel/panel-simple.c
> > > @@ -453,6 +453,7 @@ static int panel_dpi_probe(struct device *dev,
> > >   	struct panel_desc *desc;
> > >   	unsigned int bus_flags;
> > >   	struct videomode vm;
> > > +	const char *format = "";
> > >   	int ret;
> > >   	np = dev->of_node;
> > > @@ -477,6 +478,37 @@ static int panel_dpi_probe(struct device *dev,
> > >   	of_property_read_u32(np, "width-mm", &desc->size.width);
> > >   	of_property_read_u32(np, "height-mm", &desc->size.height);
> > > +	of_property_read_string(np, "bus-format", &format);
> > > +	if (!strcmp(format, "BGR888_1X24")) {
> > > +		desc->bpc = 8;
> > > +		desc->bus_format = MEDIA_BUS_FMT_BGR888_1X24;
> > > +	} else if (!strcmp(format, "GBR888_1X24")) {
> > > +		desc->bpc = 8;
> > > +		desc->bus_format = MEDIA_BUS_FMT_GBR888_1X24;
> > > +	} else if (!strcmp(format, "RBG888_1X24")) {
> > > +		desc->bpc = 8;
> > > +		desc->bus_format = MEDIA_BUS_FMT_RBG888_1X24;
> > > +	} else if (!strcmp(format, "RGB444_1X12")) {
> > > +		desc->bpc = 6;
> > > +		desc->bus_format = MEDIA_BUS_FMT_RGB444_1X12;
> > > +	} else if (!strcmp(format, "RGB565_1X16")) {
> > > +		desc->bpc = 6;
> > > +		desc->bus_format = MEDIA_BUS_FMT_RGB565_1X16;
> > > +	} else if (!strcmp(format, "RGB666_1X18")) {
> > > +		desc->bpc = 6;
> > > +		desc->bus_format = MEDIA_BUS_FMT_RGB666_1X18;
> > > +	} else if (!strcmp(format, "RGB666_1X24_CPADHI")) {
> > > +		desc->bpc = 6;
> > > +		desc->bus_format = MEDIA_BUS_FMT_RGB666_1X24_CPADHI;
> > > +	} else if (!strcmp(format, "RGB888_1X24")) {
> > > +		desc->bpc = 8;
> > > +		desc->bus_format = MEDIA_BUS_FMT_RGB888_1X24;
> > > +	} else {
> > > +		dev_err(dev, "%pOF: missing or unknown bus-format property\n",
> > > +			np);
> > > +		return -EINVAL;
> > > +	}
> > > +
> > 
> > It doesn't seem right, really. We can't the bus format / bpc be inferred
> > from the compatible? I'd expect two panels that don't have the same bus
> > format to not be claimed as compatible.
> 
> Which compatible ?
> 
> Note that this is for panel-dpi compatible, i.e. the panel which has timings
> specified in DT (and needs bus format specified there too).

panel-dpi is supposed to have two compatibles, the panel-specific one
and panel-dpi. This would obviously be tied to the panel-specific one.

Maxime

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