From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762048AbdEVUvp (ORCPT ); Mon, 22 May 2017 16:51:45 -0400 Received: from anholt.net ([50.246.234.109]:52678 "EHLO anholt.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759410AbdEVUvk (ORCPT ); Mon, 22 May 2017 16:51:40 -0400 From: Eric Anholt To: Laurent Pinchart , Archit Taneja Cc: Rob Herring , dri-devel , Thierry Reding , Mark Rutland , Andrzej Hajda , "devicetree\@vger.kernel.org" , "linux-kernel\@vger.kernel.org" Subject: Re: [PATCH 2/4] dt-bindings: Document the Raspberry Pi Touchscreen nodes. In-Reply-To: <21080088.MT6ayIGAs6@avalon> References: <20170511235625.22427-1-eric@anholt.net> <3771766.1sVmoPRjsn@avalon> <21080088.MT6ayIGAs6@avalon> User-Agent: Notmuch/0.22.2+1~gb0bcfaa (http://notmuchmail.org) Emacs/24.5.1 (x86_64-pc-linux-gnu) Date: Mon, 22 May 2017 13:51:37 -0700 Message-ID: <87pof0y5ra.fsf@eliezer.anholt.net> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha512; protocol="application/pgp-signature" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-=-= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable Laurent Pinchart writes: > Hi Archit, > > On Friday 19 May 2017 14:24:36 Archit Taneja wrote: >> On 05/18/2017 08:25 PM, Laurent Pinchart wrote: >> > On Thursday 18 May 2017 13:56:19 Archit Taneja wrote: >> >> On 05/17/2017 12:16 AM, Eric Anholt wrote: >> > >> > [snip] >> >=20 >> >>> In terms of physical connections: >> >>> [15-pin "DSI" connector on 2835] >> >>> | I2C | DSI >> >>> / \ SPI | >> >>> [TS] [Atmel]------[TC358762] >> >>> \ | >> >>> \PWM | >> >>> \ | DPI >> >>>=20 >> >>> [some backlight]------[some unknown panel] >> >>>=20 >> >>> The binding I'm trying to create is to expose what's necessary for a >> >>> driver that talks I2C to the Atmel, which then controls the PWM and = does >> >>> the command sequence over SPI to the Toshiba that sets up its end of= the >> >>> DSI link. >> >>=20 >> >> The bridge (Atmel + TC358762 combination) here looks like it's primar= ily >> >> an i2c device (i.e, the control bus is i2c). Therefore, the drm-bridge >> >> driver here should be an i2c driver instead of a mipi_dsi_driver. >> >=20 >> > Glad to see we agree, that's what I've proposed in a separate answer := -) >> > I'd go one step further though, there should be no DRM bridge, just a = DRM >> > panel. >> >> If the PCB containing the controller chips and the panel are part of a >> single casing, and the set up won't work with another panel, then yeah, I >> agree. If the bridge chips are on a separate adapter board, and there is= a >> possibility to connect other panels, then maybe a separate DRM bridge an= d a >> DRM panel might be a safer bet. > > I thought it was a single black box, but upon closer inspection there's a= =20 > separate PCB with the Microcontroller and TC358762. > > Eric, do you know if it's possible to exchange the panel for another one = (and=20 > not just an model with identical features from another vendor, but anothe= r=20 > panel with a different mode for instance) without reprogramming the=20 > microcontroller, or is the bridge board tied to the panel model ? Not without finding some other panel with equivalent non-standard connectors / doing your own soldering, at a minimum. And we don't know what kind of programming the microcontroller does, since it's a black box. --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEE/JuuFDWp9/ZkuCBXtdYpNtH8nugFAlkjT1oACgkQtdYpNtH8 nuj1Fg/8DNvblFL7gb9e/J+VffO5gjaW00p6sZsaJMCP1ur7irHwUKV3xDY8qWN4 yWwTtuAlQrP4BQG1iUoG5elP6SG0r/YM6jFvAjpWQ3WXGbs8q3IkcNgByI+Z+Osx at41zheN7eiQ4kDrYUnNOk/p1F8oEz8JQzrzi8JKkbHcip3OQmZcrsgVEITICLQ5 wo8kxGRIyaPUXU4MYqa0vGxMHEtE+d4l54dxVNdUBRMGckjg1Ad3t3fr79TY7slC xQKig08FMgnEfzGTpRIMOo4Gtx2RX1HcY8ud3mvZvEQXomvcLppCoUQW6l5OZkfB c2cdikxQQ2hGtfTNsNHn5Jz8F6N8IHEg24UGI94fsKf/+Gg79i8ULpXdKMxIv8SW c8fRWi9mWDCmdJXY6ZAg+m0raKm6T9FvZpYLfxdMQP8KwSgrToe6lXODpe3lOKXx PAKwlZ/sX2NiI4xB0sAnxQoiWiAJ06s9bUs8RnsxwwdYAKQXZ+20tO3bpW+Mu4zi lgk5znBrVI0CmKGMrVhN2m87214RTH9jRAxTdviN/XJdVIk+Zmi7Hs5Ae8j3begY Scsb1fyZeY0OQtSWesfjsP8bs65MDFfe3goVa8vK3VQ/zfIkwiioOyYT+VxWxvYH RPcEM0CmQ2pvabvu/U/AjxVNWwqimgLdzMX0N04Y5LK8uijrVns= =g+Mt -----END PGP SIGNATURE----- --=-=-=-- From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Anholt Subject: Re: [PATCH 2/4] dt-bindings: Document the Raspberry Pi Touchscreen nodes. Date: Mon, 22 May 2017 13:51:37 -0700 Message-ID: <87pof0y5ra.fsf@eliezer.anholt.net> References: <20170511235625.22427-1-eric@anholt.net> <3771766.1sVmoPRjsn@avalon> <21080088.MT6ayIGAs6@avalon> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha512; protocol="application/pgp-signature" Return-path: In-Reply-To: <21080088.MT6ayIGAs6@avalon> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Laurent Pinchart , Archit Taneja Cc: Rob Herring , dri-devel , Thierry Reding , Mark Rutland , Andrzej Hajda , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" List-Id: devicetree@vger.kernel.org --=-=-= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable Laurent Pinchart writes: > Hi Archit, > > On Friday 19 May 2017 14:24:36 Archit Taneja wrote: >> On 05/18/2017 08:25 PM, Laurent Pinchart wrote: >> > On Thursday 18 May 2017 13:56:19 Archit Taneja wrote: >> >> On 05/17/2017 12:16 AM, Eric Anholt wrote: >> > >> > [snip] >> >=20 >> >>> In terms of physical connections: >> >>> [15-pin "DSI" connector on 2835] >> >>> | I2C | DSI >> >>> / \ SPI | >> >>> [TS] [Atmel]------[TC358762] >> >>> \ | >> >>> \PWM | >> >>> \ | DPI >> >>>=20 >> >>> [some backlight]------[some unknown panel] >> >>>=20 >> >>> The binding I'm trying to create is to expose what's necessary for a >> >>> driver that talks I2C to the Atmel, which then controls the PWM and = does >> >>> the command sequence over SPI to the Toshiba that sets up its end of= the >> >>> DSI link. >> >>=20 >> >> The bridge (Atmel + TC358762 combination) here looks like it's primar= ily >> >> an i2c device (i.e, the control bus is i2c). Therefore, the drm-bridge >> >> driver here should be an i2c driver instead of a mipi_dsi_driver. >> >=20 >> > Glad to see we agree, that's what I've proposed in a separate answer := -) >> > I'd go one step further though, there should be no DRM bridge, just a = DRM >> > panel. >> >> If the PCB containing the controller chips and the panel are part of a >> single casing, and the set up won't work with another panel, then yeah, I >> agree. If the bridge chips are on a separate adapter board, and there is= a >> possibility to connect other panels, then maybe a separate DRM bridge an= d a >> DRM panel might be a safer bet. > > I thought it was a single black box, but upon closer inspection there's a= =20 > separate PCB with the Microcontroller and TC358762. > > Eric, do you know if it's possible to exchange the panel for another one = (and=20 > not just an model with identical features from another vendor, but anothe= r=20 > panel with a different mode for instance) without reprogramming the=20 > microcontroller, or is the bridge board tied to the panel model ? Not without finding some other panel with equivalent non-standard connectors / doing your own soldering, at a minimum. And we don't know what kind of programming the microcontroller does, since it's a black box. --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEE/JuuFDWp9/ZkuCBXtdYpNtH8nugFAlkjT1oACgkQtdYpNtH8 nuj1Fg/8DNvblFL7gb9e/J+VffO5gjaW00p6sZsaJMCP1ur7irHwUKV3xDY8qWN4 yWwTtuAlQrP4BQG1iUoG5elP6SG0r/YM6jFvAjpWQ3WXGbs8q3IkcNgByI+Z+Osx at41zheN7eiQ4kDrYUnNOk/p1F8oEz8JQzrzi8JKkbHcip3OQmZcrsgVEITICLQ5 wo8kxGRIyaPUXU4MYqa0vGxMHEtE+d4l54dxVNdUBRMGckjg1Ad3t3fr79TY7slC xQKig08FMgnEfzGTpRIMOo4Gtx2RX1HcY8ud3mvZvEQXomvcLppCoUQW6l5OZkfB c2cdikxQQ2hGtfTNsNHn5Jz8F6N8IHEg24UGI94fsKf/+Gg79i8ULpXdKMxIv8SW c8fRWi9mWDCmdJXY6ZAg+m0raKm6T9FvZpYLfxdMQP8KwSgrToe6lXODpe3lOKXx PAKwlZ/sX2NiI4xB0sAnxQoiWiAJ06s9bUs8RnsxwwdYAKQXZ+20tO3bpW+Mu4zi lgk5znBrVI0CmKGMrVhN2m87214RTH9jRAxTdviN/XJdVIk+Zmi7Hs5Ae8j3begY Scsb1fyZeY0OQtSWesfjsP8bs65MDFfe3goVa8vK3VQ/zfIkwiioOyYT+VxWxvYH RPcEM0CmQ2pvabvu/U/AjxVNWwqimgLdzMX0N04Y5LK8uijrVns= =g+Mt -----END PGP SIGNATURE----- --=-=-=-- -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html