From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thierry Reding Subject: Re: ARM topic: Is DT on ARM the solution, or is there something better? Date: Mon, 18 Nov 2013 16:29:21 +0100 Message-ID: <20131118152920.GL26046@ulmo.nvidia.com> References: <52644A9E.3060007@wwwdotorg.org> <20131118122644.GA26046@ulmo.nvidia.com> <20131118134022.26EE7C409EC@trevor.secretlab.ca> <20131118135727.GD14306@sirena.org.uk> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="f54savKjS/tSNRaU" Return-path: Content-Disposition: inline In-Reply-To: <20131118135727.GD14306-GFdadSzt00ze9xe1eoZjHA@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Mark Brown Cc: Grant Likely , Stephen Warren , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "ksummit-2013-discuss-cunTk1MwBs98uUxBSJOaYoYkZiVZrdSR2LY78lusg7I@public.gmane.org" , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" List-Id: devicetree@vger.kernel.org --f54savKjS/tSNRaU Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Nov 18, 2013 at 01:57:27PM +0000, Mark Brown wrote: > On Mon, Nov 18, 2013 at 01:40:22PM +0000, Grant Likely wrote: >=20 > > Some hardware does that. That's what OHCI, EHCI, UHCI, XHCI, SDHCI, and > > similar are all about. It always helps when well understood hardware > > follows a register interface. It doesn't work for everything, but I > > agree it would be good to have preferred hw interfaces for SPI & I2C. >=20 > You'd need something class based like USB, there's such massive > variation in what the hardware is trying to do and the tradeoffs. A big > issue is that especially with I2C many of the devices are primarily > analogue devices implemnted in larger processes where the cost of adding > additional digital logic can have a noticeable effect on the area and > hence cost of the silicon. My comments were mostly regarding the interface controllers. Those which generate the same bus transactions but need different drivers on every SoC. I suspect that the same costs don't apply (or at least not to the same extent) to SoCs. Thierry --f54savKjS/tSNRaU Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (GNU/Linux) iQIcBAEBAgAGBQJSijJQAAoJEN0jrNd/PrOh28EP/joNivci+QGrcJqXlT1SkBaQ Ah1GSk98FjQM+jH/N6iVXzV3ybYdAyUp3mWh2SzrXa5GLah1/VhPz4kvBR4cWb6v hIMwrqGt+LT+xS19U/fpN7YgXvVKgU4CUE+gLeEx8/p3SPJ+KN0svjV2B4Gs/x9c olLaS4Zo11Uv5rT2UWcrCe5OyMpq8PR4NBQswFQxssOUeSLCwX8c4gSbh2areJVS 5AImgCyyH06jxk3cAuS1IOnAwflZoZSjOu7XzzFFeL403SBbgvPcf9R4bM4Kz7Vi Yy79r4+w6MwRZjKke85Zf1tF2OY5NsqSYDi+4SpMRsF3cfmZI5r1yLahdacfQp84 CdTN1UsnnhRocXUDth2CJ9naqatfUf20H7OIWshUFt2gMr8pEXegu1axFDMDPm2i O8L87lzrZwgmD3bpYRQZanW42V/XqMVdPg9Y55D9scSmLYa7Gf8WX/u6O1e7/A6i WLKTDmbkFNnnhhqj63a0fPMLT2yx4frIkW50YS8lTiCtgUcKvroVTZyrCv+kwqnW HL+jo9GeFY8+7qCKOytRx6Y1gMov8wmRDUDgwkmYPPn6TFBENijxN+SKLzJYycB0 2NyOG3Fx87kLno3vpgIx/5CDhSiyCfYPGCNCJjiSQMM4W40/LPlv+NhqXxxR9Srr QSsC7a8201AeitN89sQe =f/e6 -----END PGP SIGNATURE----- --f54savKjS/tSNRaU-- -- 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