Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754442AbcCRUeL (ORCPT ); Fri, 18 Mar 2016 16:34:11 -0400 Received: from mezzanine.sirena.org.uk ([106.187.55.193]:43878 "EHLO mezzanine.sirena.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751200AbcCRUeH (ORCPT ); Fri, 18 Mar 2016 16:34:07 -0400 Date: Fri, 18 Mar 2016 20:33:52 +0000 From: Mark Brown To: Maxime Ripard Cc: Michal Suchanek , Priit Laes , Chen-Yu Tsai , linux-spi , "linux-arm-kernel@lists.infradead.org" , Linux Kernel Mailing List , Emilio =?iso-8859-1?Q?L=F3pez?= Message-ID: <20160318203352.GL2566@sirena.org.uk> References: <1456466217-6793-2-git-send-email-plaes@plaes.org> <20160226122504.GR18327@sirena.org.uk> <20160306214206.GW8418@lukather> <20160317072721.GJ30977@lukather> <20160317114308.GF2566@sirena.org.uk> <20160318202310.GS30977@lukather> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="ZGtad4bun3m+J/4B" Content-Disposition: inline In-Reply-To: <20160318202310.GS30977@lukather> X-Cookie: Walk softly and carry a megawatt laser. User-Agent: Mutt/1.5.24 (2015-08-30) X-SA-Exim-Connect-IP: 2a01:348:6:8808:fab::3 X-SA-Exim-Mail-From: broonie@sirena.org.uk Subject: Re: [PATCH 1/2] spi: sun4i: add DMA support X-SA-Exim-Version: 4.2.1 (built Mon, 26 Dec 2011 16:24:06 +0000) X-SA-Exim-Scanned: Yes (on mezzanine.sirena.org.uk) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1490 Lines: 38 --ZGtad4bun3m+J/4B Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Fri, Mar 18, 2016 at 09:23:10PM +0100, Maxime Ripard wrote: > On Thu, Mar 17, 2016 at 12:54:08PM +0100, Michal Suchanek wrote: > > Very few device drivers would work with 63byte transfers only and the > > code for manually driving the CS line in case the DMA engine fails to > > configure will necessarily go untested most of the time since most > > systems will have DMA configured properly. > That's not true. A significant portion would work. I don't like to > make up numbers, but I guess only the EEPROMs and rather big screens > wouldn't work. You'll probably also see devices doing things like firmware downloads, there's a bunch of applications for larger transfers. Like you say it's definitely not going to be a universal problem though, there's many devices that just use SPI for fast register access. --ZGtad4bun3m+J/4B Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAEBCAAGBQJW7GYvAAoJECTWi3JdVIfQ0CEH/33CMWaBMWHbwpSnvixBuzXl 5ZLE1wmb2LHvqNuVsOvuCj4O3AFWq3UNS7citObZ4+W/rlQkehMekvh3l3xjO0En pRnuRe8+s2mFpcvhMFlcWzdk8FTv1iF2TnFIdRnHjACjYw73Xv8TuDTo286Qc++L XDLkpT5Pq8bcGa805nnd5DgiOOGsJTdmAZUfvDLyuXtop7nc9OpvJg0cutCdycRr FZv08xrvhn+G6fvJ1pavIIXebTIFh4U2C77Rc1ap7qXYBd/AvpVGIf6Gs/sYyUyG hOoD4TmFG02NZbyGffev5vRgpthR+m9kxEVDFuWWyO6LCLGzxN+ZhBAE/llVTKE= =Puwx -----END PGP SIGNATURE----- --ZGtad4bun3m+J/4B--