From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754110AbcEaN12 (ORCPT ); Tue, 31 May 2016 09:27:28 -0400 Received: from mezzanine.sirena.org.uk ([106.187.55.193]:57878 "EHLO mezzanine.sirena.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753290AbcEaN1X (ORCPT ); Tue, 31 May 2016 09:27:23 -0400 Date: Tue, 31 May 2016 14:27:07 +0100 From: Mark Brown To: Michal Suchanek Cc: Geert Uytterhoeven , linux-sunxi , Maxime Ripard , Chen-Yu Tsai , linux-spi , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" Message-ID: <20160531132706.GC29837@sirena.org.uk> References: <20160530112610.GJ29837@sirena.org.uk> <20160530150343.GL29837@sirena.org.uk> <20160530155016.GO29837@sirena.org.uk> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="h4FfhoHh9AMwLYAn" Content-Disposition: inline In-Reply-To: X-Cookie: Happy feast of the pig! User-Agent: Mutt/1.6.0 (2016-04-01) X-SA-Exim-Connect-IP: 2a01:348:6:8808:fab::3 X-SA-Exim-Mail-From: broonie@sirena.org.uk Subject: Re: [PATCH 5/5] RFC 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 --h4FfhoHh9AMwLYAn Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Tue, May 31, 2016 at 12:44:54PM +0200, Michal Suchanek wrote: > On 30 May 2016 at 17:50, Mark Brown wrote: > > On Mon, May 30, 2016 at 05:28:10PM +0200, Michal Suchanek wrote: > >> It's what the driver did to start with and it was requested to fall > >> back to non-DMA in the case DMA is not available. > > Why? I really can't see any sensible use case for this that doesn't > > have a better solution available. > Of course, the solution is to compile in the DMA driver. > It's been argued that some drivers which use only short transfers will > just work. With nothing else in the system that needs DMA? It's making the performance of the system less reliable for the benefit of a very narrow use case. --h4FfhoHh9AMwLYAn Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAEBCAAGBQJXTZEpAAoJECTWi3JdVIfQbikH/2j2gk2FcfH9F0GoOWB4zpSN mt+ESA5fCo0B9NeRtOw3I+nFCoueRj8lujGQSFo1jXMoe4tqW1ZfH22CWPGeZSO2 u6OO6PZvP4v6ggdV/RqOWLPGQJ56wbs9Wdnzvd0It+WoUxb7uhhTr1Q3nAV6HKWp qvm6LtJu79/mcP4vQxagcTAmtcdcc4K8GviTIcgKO4jXMHwHGXwYJb7bETk9zVvA 83cRQN3oopHSZTGZwIIWn263ObDQI1taCRvb29ks/vPpE5ukqeT/uv3WGzb/VsOK vdw/yAIjg7oSxIHgOF2LCtRyM6bhmideCwatp8bN6NHbpBmzoEV87/tN+rEvEzI= =anrG -----END PGP SIGNATURE----- --h4FfhoHh9AMwLYAn--