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 13:50:14 -0700 Message-ID: <87shjwy5tl.fsf@eliezer.anholt.net> References: <20170511235625.22427-1-eric@anholt.net> <3768334.nZM7df9y4L@avalon> <87shk4iqr7.fsf@eliezer.anholt.net> <5108517.4KFRtigegR@avalon> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha512; protocol="application/pgp-signature" Return-path: In-Reply-To: <5108517.4KFRtigegR@avalon> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Laurent Pinchart Cc: Rob Herring , dri-devel , Thierry Reding , Mark Rutland , Archit Taneja , 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 Eric, > > On Tuesday 16 May 2017 11:46:36 Eric Anholt wrote: > > [snip] > >> In terms of physical connections: >>=20 >> [15-pin "DSI" connector on 2835] >>=20 >> | I2C | DSI >> / \ SPI | >> [TS] [Atmel]------[TC358762] >> \ | >> \PWM | >> \ | DPI >> [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. > > According to the documentation I've been able to find, the TC358762 has a= n SPI=20 > master port through which it can output the commands DCS received from th= e DSI=20 > port, and an I2C slave port through which it can be configured by an exte= rnal=20 > device. If the connection between the microcontroller and the TC358762 is= =20 > indeed SPI and not I2C, I assume it's used by the microcontroller to rece= ive=20 > the DCS commands and perform control of the backlight (and possibly other= =20 > components) accordingly. By the way, is there any place where I can find = a=20 > leaked version of the non-public panel schematics ? ;-) Not that I know of. I don't know that you can control the backlight over DCS, given that I have no docs. We only send commands from Atmel to TC, not the other way around. > As far as I can tell from your patch series, you don't need to send any=20 > command to the TC358762 over DSI. In that case I would model the panel in= DT=20 > as an I2C device, as all control goes through the I2C bus. The DSI video = data=20 > connection should then be modelled using the OF graph DT bindings. The re= sult=20 > will be a black box panel with a custom black box panel driver, using a s= ingle=20 > DT node. There's no need for a separate bridge instance. That's the clean= est=20 > option I can come up with so far, and I agree that splitting TC358762 sup= port=20 > into a standalone bridge driver makes no sense in this case. I agree, it's just that when I submitted to drm-panel I was told that it didn't make sense as a single driver, so I went to all of this work instead. --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEE/JuuFDWp9/ZkuCBXtdYpNtH8nugFAlkjTwYACgkQtdYpNtH8 nuiJEw//fSQr6B46ATrYPPQNK3IzeujgQUlosBpmxPEt90wHoB9VTgXqh5EuOr2A X0koMfUHCRUEvkIT7BWlZVxlN5XXOXnZtn784Qz/qP9cdNyEcjYZG+D5DDLEYeQV jaqzEuIPxx83vNqt2HVz11KZQKe0hy4NLTycvHGa78mLk+jLFipkJZhGgXNYO8D/ MSj7GGAP0l6zctO5UMOqRic9r2xhTAcCLpjnpV8CcGUEHx2fJYN9oaKjxTPn8lPF 9T/Iuc8MLf8CS/UinUZumD91J0sxgPsG/zzaRsbNQ9gm3m0/c7beeB2AH342RtHq rmwNaDVx9QNzKdOWlVYddCr7M9k3z4O1j+1c61xXvHGebWpJ++KKuwpp9hvd9DdH S8PKK92RpV4SO7ki8ocYJwYBx6OjoysN5i8E/1zlxkvuAi78Pvin1xEvWSs/xKjP fXTSAXxaDkLjSQfWoS/D1harFCPKrUhigDsU6d/XlIh019cPAGyHULQK3jCeK6ZQ ztJ5Ud0gCQTnNfenph+ZzQxVD4kG2Rw5PSu8JeWpeNCb/EnNFD/cWFQFV/DSWX0f gT47xDLnjrNCAfFgflDcahIRKBoFvruTg4OG8hapNHq0xX+zT0Ksh0W8YbxFMSao E4PIjaj5tCxQqitWF31nHahxsjTx+sEjcBLPi9iVenQnYhSJlTg= =MDFp -----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