From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thierry Reding Subject: Re: [Ksummit-2013-discuss] ARM topic: Is DT on ARM the solution, or is there something better? Date: Tue, 22 Oct 2013 11:39:24 +0200 Message-ID: <20131022093923.GC15640@ulmo.nvidia.com> References: <52644A9E.3060007@wwwdotorg.org> <20131020220839.GT2443@sirena.org.uk> <5264576F.6050307@wwwdotorg.org> <52658EBC.8020800@wwwdotorg.org> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="7gGkHNMELEOhSGF6" Return-path: Content-Disposition: inline In-Reply-To: Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Nicolas Pitre Cc: Stephen Warren , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "ksummit-2013-discuss-cunTk1MwBs98uUxBSJOaYoYkZiVZrdSR2LY78lusg7I@public.gmane.org" , Mark Brown , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" List-Id: devicetree@vger.kernel.org --7gGkHNMELEOhSGF6 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Oct 21, 2013 at 04:40:15PM -0400, Nicolas Pitre wrote: > On Mon, 21 Oct 2013, Stephen Warren wrote: [...] > > but taking the big picture into > > account, observe that we make life a lot more difficult for distros, > > since they need to get the device tree from somewhere. Distros now are > > forced to work out which DTB goes with which board, >=20 > This is not a new problem. Before you had to figure out which kernel=20 > would go with which board. You still need to match kernels to boards even with DT. It's no good if you provide a full DTB that describes your hardware if the kernel doesn't support any of it. > > or perhaps we need > > to define a firmware interface to obtain the DTB and pass it to the > > kernel. >=20 > That's the bootloader's job. Nothing magical actually: just have U-Boot= =20 > or whatever load the DTB from some flash area. I agree. I think most if not all architectures that support DT have long had some interface on how to pass a DTB to the kernel. At least I know that ARM and x86 have, but I'm pretty sure that PowerPC, SPARC and others do too. > > I > > think we can still have a hack-free, churn-free, multi-platform kernel > > without requiring DT, but by using board files. >=20 > I kinda agree with you, but this is too late for that now. >=20 > We have DT, and the best way forward is to fix the process which is,=20 > arguably, somewhat obstructive and broken at the moment. I agree that the process could use some enhancements. But I also think that we should be open to move away from DT again if it turns out to not be a good enough solution. "It's too late" doesn't sound like a very good argument to me. Essentially DT is just a different way to represent what we used to have in platform data, so we haven't fundamentally changed anything at that level. Well, we've made things worse to some degree. Thierry --7gGkHNMELEOhSGF6 Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (GNU/Linux) iQIcBAEBAgAGBQJSZkfLAAoJEN0jrNd/PrOhvVAP/0IAQtthlp/R0fASjpcWErPX sSTYL9ivY8Rjqp+Z/lCK6LHnTed7NoUxZHFrIINGbOqDgjc4cxd+3wkwoA3pLb6e CIkXi2nCh3SaFvNh8vEb7IdCDhcVUel064kKKxJ5XGK7/3EkUgUPXcD3ChXWEf0N QXMEGZr7Lu2UEpOFDWYZjsxfrzYtxN0v4CAbiIemIvsMFksxWFarfs913Pgh9+U3 uFFZg2CBRoiWAiQPDSqP8cyud/m/Eer2OpIEY5HzeOwk35VrekJwczUA+S4zo1Oa b7OWssHze6WcCTBB1dMzQzJW2YNMZJgnkfcoKRUBG1BNLtGS08FNHo/Pkn6V/qoe b7uPYIbehW/mCE52ERdeXH/WxsSFx/Aw8HLECREmqFV6TMCtp+lY5uAyKFIodgsb kLkdX1Yx/ZwKbThq5G0lvvigYAzOUl1ThTf4QSiErGvIgbNCKcrCAUkk3U1IjgA/ QKnsGS0GUCuAyeiI/jO6am7POLzFr5Ik/xcK+eVHtmMEZXlkVyL6QqoPcTO7Z0VO yKCVwe0Dn3VopESSHLC3j9u5xU5lRTz7yp3DM/9jvGkTUOdj3j48r1S7+Tk0CS+C tVsTpzbzofCqOzJJdrmwkZuAAJkqrnQLIZ7CokJ3eAjiIUmQe2hqCx5c2QiknXRh dKJ+ZKgSvfakEbqi8pKL =7hH+ -----END PGP SIGNATURE----- --7gGkHNMELEOhSGF6-- -- 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