Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935669AbcCQLna (ORCPT ); Thu, 17 Mar 2016 07:43:30 -0400 Received: from mezzanine.sirena.org.uk ([106.187.55.193]:39540 "EHLO mezzanine.sirena.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933349AbcCQLn2 (ORCPT ); Thu, 17 Mar 2016 07:43:28 -0400 Date: Thu, 17 Mar 2016 11:43:08 +0000 From: Mark Brown To: Michal Suchanek Cc: Maxime Ripard , 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: <20160317114308.GF2566@sirena.org.uk> References: <1456466217-6793-1-git-send-email-plaes@plaes.org> <1456466217-6793-2-git-send-email-plaes@plaes.org> <20160226122504.GR18327@sirena.org.uk> <20160306214206.GW8418@lukather> <20160317072721.GJ30977@lukather> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="nYjNOXWpwjVqWAsU" Content-Disposition: inline In-Reply-To: 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: 1398 Lines: 36 --nYjNOXWpwjVqWAsU Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Thu, Mar 17, 2016 at 11:58:05AM +0100, Michal Suchanek wrote: > On 17 March 2016 at 08:27, Maxime Ripard > > You're mixing two things up: the fact that we can't do more than the > > FIFO length in PIO and that we're missing DMA support. We have patches > > to address both, and there's no depedency between the two. > The only thing is that although DMA is optional on pretty much any > system you will have DMA available unless you broke your config. You > really do want the DMA support when it is available. So there will be > nobody testing the non-DMA part and it will be prone to bitrot. Well, it might be worth doing PIO for very short transfers even if you have DMA - it's quite common for this to perform better. --nYjNOXWpwjVqWAsU Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAEBCAAGBQJW6phEAAoJECTWi3JdVIfQ/sYH/1nmKqQ6Kvej3uyHfBm8xUpE FCQx45QqITlfNBORJz0nykBe35bhOkMVQQeApGMX9WXOF4VOA/3P6Jq3wi7WPSoJ 0tuTrfarY14HcTRan3nOdD5k2T5vwpmBlettP+iu8erJUDP3UzA0kzMpi1cvLUfm YVnF1woIlaQ9uExmm7Qr4f4B29h4q/bK8r1/keB+0riREKvJafLlP6lMQ7pkslVj yimiQe44aMOWtxB1zfDpLD8tyEqpXWUnxe/s1hT70AAHswQo9P+GtYl4L36fFnMN o3IwqHxxkv8mTDuHFpNghXf4h7BnOua6QkBJSqa1EgKlYS6atsbZM7uP1OI+gv8= =Q7vu -----END PGP SIGNATURE----- --nYjNOXWpwjVqWAsU--