From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thierry Reding Subject: Re: [RESEND PATCH v3 06/11] drm: add DT bindings documentation for atmel-hlcdc-dc driver Date: Mon, 21 Jul 2014 14:56:26 +0200 Message-ID: <20140721125624.GF15238@ulmo> References: <1404751384-5077-1-git-send-email-boris.brezillon@free-electrons.com> <1404751384-5077-7-git-send-email-boris.brezillon@free-electrons.com> <20140714100542.GB9870@ulmo> <20140715120619.7f29c458@bbrezillon> <20140715103136.GA6616@ulmo> <20140718165152.0a9fde09@bbrezillon> <20140721121513.GB15238@ulmo> <20140721143321.5bda6ea9@bbrezillon> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============0261748964==" Return-path: In-Reply-To: <20140721143321.5bda6ea9@bbrezillon> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: Boris BREZILLON Cc: Mark Rutland , devicetree@vger.kernel.org, Nicolas Ferre , dri-devel@lists.freedesktop.org, Alexandre Belloni , Laurent Pinchart , Bo Shen , Lee Jones , Jean-Jacques Hiblot , Samuel Ortiz , Tim Niemeyer , Jean-Christophe Plagniol-Villard , linux-pwm@vger.kernel.org, Pawel Moll , Ian Campbell , Rob Herring , Andrew Victor , linux-arm-kernel@lists.infradead.org, Thomas Petazzoni , Kumar Gala List-Id: devicetree@vger.kernel.org --===============0261748964== Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="Y/WcH0a6A93yCHGr" Content-Disposition: inline --Y/WcH0a6A93yCHGr Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Jul 21, 2014 at 02:33:21PM +0200, Boris BREZILLON wrote: > On Mon, 21 Jul 2014 14:15:16 +0200 > Thierry Reding wrote: >=20 > > On Fri, Jul 18, 2014 at 04:51:52PM +0200, Boris BREZILLON wrote: > > > Hi Thierry, > > >=20 > > > Oops, I missed this reply. > > >=20 > > > On Tue, 15 Jul 2014 12:31:37 +0200 > > > Thierry Reding wrote: > > >=20 > > > > On Tue, Jul 15, 2014 at 12:06:19PM +0200, Boris BREZILLON wrote: > > > > > On Mon, 14 Jul 2014 12:05:43 +0200 Thierry Reding wrote: > > > > > > On Mon, Jul 07, 2014 at 06:42:59PM +0200, Boris BREZILLON wrote: > > > > [...] > > > > > > > diff --git a/Documentation/devicetree/bindings/drm/atmel-hlcd= c-dc.txt b/Documentation/devicetree/bindings/drm/atmel-hlcdc-dc.txt > > > > > > [...] > > > > > > > +The Atmel HLCDC Display Controller is subdevice of the HLCDC= MFD device. > > > > > > > +See Documentation/devicetree/bindings/mfd/atmel-hlcdc.txt fo= r more details. > > > > > >=20 > > > > > > I think it's better to refer to these using relative filenames.= When the > > > > > > device tree bindings are moved out of the kernel tree, they may= no > > > > > > longer use the same hierarchy. > > > > >=20 > > > > > Sure. > > > > > By relative path you mean ../../mfd/atmel-hlcdc.txt or just > > > > > mfd/atmel-hlcdc.txt ? > > > >=20 > > > > I think the former is more explicit. > > >=20 > > > Okay. > > >=20 > > > >=20 > > > > > > > + - atmel,panel: Should contain a phandle with 2 parameters. > > > > > > > + The first cell is a phandle to a DRM panel device > > > > > > > + The second cell encodes the RGB mode, which can take the = following values: > > > > > > > + * 0: RGB444 > > > > > > > + * 1: RGB565 > > > > > > > + * 2: RGB666 > > > > > > > + * 3: RGB888 > > > > > >=20 > > > > > > These are properties of the panel and should be obtained from t= he panel > > > > > > directly rather than an additional cell in this specifier. > > > > >=20 > > > > > Okay. > > > > > What's the preferred way of doing this ? > > > > > What about defining an rgb-mode property in the panel node. > > > >=20 > > > > There's .bpc in struct drm_display_info, I suspect that it could be= used > > > > for this. Alternatively, maybe we could extend the list of color fo= rmats > > > > that go into drm_display_info.color_formats? RGB444 is already cove= red. > > >=20 > > > I don't think this color_formats field is intended to represent data > > > stream format going through the bus. > > > Moreover, AFAIU, RGB444 in this definition represent RGB 4:4:4 (chroma > > > subsampling rate) and not 12 bits signals (4 bits for each color). > > >=20 > > > Anyway I'll propose a patch series adding a new field to > > > drm_display_info to encode the mediabus format (as discussed with > > > Laurent and you). > > >=20 > > > >=20 > > > > Also, like Laurent said, this shouldn't go into the device tree, si= nce > > > > it's already implied by the panel's compatible value, so we'd be > > > > duplicating information. > > >=20 > > > Again, this is not necessarily true (depending on your board design). > > > One can decide to connect an RGB888 panel on an RGB666 bus and connect > > > the missing pins to ground. > >=20 > > I think in that case the board design itself could be considered as an > > RGB888 to RGB666 bridge, and I think that's what the device tree should > > be describing rather than a panel with a variable number of input > > formats. >=20 > So, you're suggesting to add an RGB to RGB drm_bridge driver (and > the appropriate DT bindings) to handle this case, right ? Yes, exactly. Thierry --Y/WcH0a6A93yCHGr Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBAgAGBQJTzQ34AAoJEN0jrNd/PrOhN1EP/20lQDIjPPUQj2DRQdvKtOeU 7zRyNlDQPismCfs1smIB3nqxkGpvA/tU4TcbHKbyr1fRgq2GZ+/1CloaZTgHy3Ly ObGTd7MXZR8HydIYxwumbBvHaWgYVfa0z8/7A4slM46XQytT2unri6onjnTC+Lfn C+xP5h4AZpyn/BAcezksV8WfIthZvjhrSu8sSYIQqruyBYIqWRU3vniYX+rWTthw hMfRRr4AuKCInL4fQnJu1HLVZxdY9vvDLzOqYrwVsMBQa82t/mS/giC0r8eY7+MN yQuJ4QhF11SZsCRpRji17dXLfHs+/X+lzKTwRkQoDk+H1kOqaDFLdPBEbXx6l8eL GX+qfRvNKzPTzhIa2doqJuB3Dcpt4OfiVvHPhxi2zH7kGi5cfPpusK0xf55ZZO1I 49MzqYW8c6X3eWWv5QB0Tk4nEKMmXw0YdAIxNBEs7Y5VZo8QoKq2xWnF6QOUZVdV L85QZuQFL+SW/XuG99eJn61ILBHMLuZX6wu2y3APCEoJVM1cTjy+oSOgxzDibLDF G/ghkAfSYoyQ8Mx4U5gOnEWDcvnO0AE5JKfFqmIP0Pe5wD0vxyeUIDboDpQ9I0ol Gzcnc5+e4R/oGQSQGdD4qhjjJUsyzQdS+Un0iqraI7ZEvP+CL6hnYYLNx406Clhg 01l7z8dvbIlTsFuWner3 =OWNM -----END PGP SIGNATURE----- --Y/WcH0a6A93yCHGr-- --===============0261748964== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/dri-devel --===============0261748964==--