Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932548AbcJTKWr (ORCPT ); Thu, 20 Oct 2016 06:22:47 -0400 Received: from bear.ext.ti.com ([198.47.19.11]:52662 "EHLO bear.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756127AbcJTKWp (ORCPT ); Thu, 20 Oct 2016 06:22:45 -0400 Subject: Re: [PATCH 2/2] ARM: dts: da850: add a node for the LCD controller To: Sekhar Nori , Bartosz Golaszewski References: <1475672732-17111-1-git-send-email-bgolaszewski@baylibre.com> <65fde145-0820-794d-d345-621f66cdacc0@ti.com> <7a2ffcd0-fe1d-c887-53b7-7cb5e1e61222@ti.com> <4975084.EGQPv58AK6@avalon> <6c6fcceb-c6f2-219d-492a-a8b38fd83093@ti.com> CC: Laurent Pinchart , Kevin Hilman , Michael Turquette , Rob Herring , Frank Rowand , Mark Rutland , Peter Ujfalusi , Russell King , Karl Beldan , LKML , arm-soc , linux-drm , linux-devicetree , Jyri Sarha , David Airlie , Maxime Ripard , Karl Beldan From: Tomi Valkeinen Message-ID: Date: Thu, 20 Oct 2016 13:21:47 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.3.0 MIME-Version: 1.0 In-Reply-To: <6c6fcceb-c6f2-219d-492a-a8b38fd83093@ti.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="e8eufdJ916Lqei41WJcklLmckPut3tt7O" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4071 Lines: 93 --e8eufdJ916Lqei41WJcklLmckPut3tt7O Content-Type: multipart/mixed; boundary="bAQc3IKvMW23rFA7e6CEFmCFKLiXId4b8"; protected-headers="v1" From: Tomi Valkeinen To: Sekhar Nori , Bartosz Golaszewski Cc: Laurent Pinchart , Kevin Hilman , Michael Turquette , Rob Herring , Frank Rowand , Mark Rutland , Peter Ujfalusi , Russell King , Karl Beldan , LKML , arm-soc , linux-drm , linux-devicetree , Jyri Sarha , David Airlie , Maxime Ripard , Karl Beldan Message-ID: Subject: Re: [PATCH 2/2] ARM: dts: da850: add a node for the LCD controller References: <1475672732-17111-1-git-send-email-bgolaszewski@baylibre.com> <65fde145-0820-794d-d345-621f66cdacc0@ti.com> <7a2ffcd0-fe1d-c887-53b7-7cb5e1e61222@ti.com> <4975084.EGQPv58AK6@avalon> <6c6fcceb-c6f2-219d-492a-a8b38fd83093@ti.com> In-Reply-To: <6c6fcceb-c6f2-219d-492a-a8b38fd83093@ti.com> --bAQc3IKvMW23rFA7e6CEFmCFKLiXId4b8 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 20/10/16 13:07, Sekhar Nori wrote: > Per me, compatible property is an ordered list precisely for the reason= > that things should continue to "work" with as closely matched driver as= > possible. So even if someone is running a kernel which does not > recognize "ti,da850-tilcdc", it should still be able to probe the drive= r > based on "ti,am33xx-tilcdc" and provide as close to full functionality > as possible. >=20 > That said, I will not insist on keeping it around if Tomi is > uncomfortable. And having read the binding documentation accepted by > Jyri, it actually says the compatible property should be __one of__ > "ti,am33xx-tilcdc" or "ti,da850-tilcdc". Well, they are just not compatible as far as I know. If the LCDC on DA850 would be identified as AM335x LCDC, and used as such, it would not work at all. They have different registers, AM335x LCDC has registers that do not exist on DA850. With our driver it happens to work, because the driver looks at the IP revision in the registers, and then decides that this IP is not AM335x LCDC even if the dts says so. But I see that as a driver "feature", nothing that the .dts can depend on. Perhaps it might work the other way around, using DA850 driver on AM335x, as DA850 LCDC is a kind of subset of AM335x LCDC. But I'm not sure even about that. Tomi --bAQc3IKvMW23rFA7e6CEFmCFKLiXId4b8-- --e8eufdJ916Lqei41WJcklLmckPut3tt7O Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBCAAGBQJYCJq7AAoJEPo9qoy8lh71POQP/jlaeC0j1O9fbewFkCU3/QXW 6Si5P81GkRed7RYPxWs0oauXwxKdk5PaeUPeIDKhox6jXwFETe/d6VfxiE650W91 yEMxl9ji91Kt3vIru+68OwbglTv27DVQTniLOzg28niUxWcBaZZ3Ib33MoWMK7Ar PmD5pjax76datyvVC+h5CfmBWKnDRoJYoSZXaZIWtzkXLyUUMRRERykUtoata2b+ 7Btdi1z1yCZ7TGM4J15mu5pmyxB+1e7tzq/rnEQaBCFGj0VtU4ZubvK0vpsmQ6Li KOju4saSo4uTtrSZPsOo/jE5qk4l8JQjIZwwaIcRPnfLXz2I1XjWmrW/mmu5JjW3 qBuJQA0TIKyCOc4OePwtCS0adceZGX0lNGwln1O0vqSgGFskiUkVWAKrZktjX8Db F7EpWw/Y8OfBBQLTpH9M4JIqXZUt+LAqnFwZyO3kviHyPSg5S7T5/cZQlnaKqls/ Xj+u0eQ2CHOg9fdITPVwFQ+JG/Bi62GgP3D3rbN6ORWnOseFX0OsMg5AUP+zEJYM HyRj5MycHbO+pisVPuG71ssKv/tMmRY4V1jhy0+1/jLX/QQ4k6GAC8LToV0KZ4dg kPNAKYc8f0NFEUpXmg+OOebkgeUpHly3U3HCNKxVdYOMb23T7MN7cgGduB6QZbzu CqoCcmHO1zOKhvWY2J2r =p1Yo -----END PGP SIGNATURE----- --e8eufdJ916Lqei41WJcklLmckPut3tt7O--