From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754856Ab3GPKEi (ORCPT ); Tue, 16 Jul 2013 06:04:38 -0400 Received: from cassiel.sirena.org.uk ([80.68.93.111]:40477 "EHLO cassiel.sirena.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754159Ab3GPKEg (ORCPT ); Tue, 16 Jul 2013 06:04:36 -0400 Date: Tue, 16 Jul 2013 11:03:57 +0100 From: Mark Brown To: Lars-Peter Clausen Cc: Vinod Koul , Liam Girdwood , alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org Message-ID: <20130716100357.GE22506@sirena.org.uk> References: <1373906531-6938-1-git-send-email-lars@metafoo.de> <20130715172643.GZ11538@sirena.org.uk> <20130715165721.GV16653@intel.com> <20130715175726.GA11538@sirena.org.uk> <51E43D6C.1050000@metafoo.de> <20130715195145.GB11538@sirena.org.uk> <51E50D3B.2050207@metafoo.de> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="n+lFg1Zro7sl44OB" Content-Disposition: inline In-Reply-To: <51E50D3B.2050207@metafoo.de> X-Cookie: Many pages make a thick book. User-Agent: Mutt/1.5.21 (2010-09-15) X-SA-Exim-Connect-IP: 94.175.92.69 X-SA-Exim-Mail-From: broonie@sirena.org.uk Subject: Re: [RFC 1/2] ASoC: dmaengine-pcm: Add support for querying DMA capabilities X-SA-Exim-Version: 4.2.1 (built Mon, 26 Dec 2011 16:57:07 +0000) X-SA-Exim-Scanned: Yes (on cassiel.sirena.org.uk) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --n+lFg1Zro7sl44OB Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Tue, Jul 16, 2013 at 11:07:07AM +0200, Lars-Peter Clausen wrote: > I would assume that most of them don't express hardware limitations but > rather are sensible lower limits which allow operation without > over-/underruns. But that's something that doesn't necessarily depend on the Yes, indeed. Or just cut'n'pasted from some other driver without much thought. > DMA controller, but rather on the system as a whole, e.g. on a slower > machine you'd typically set the limit higher so the CPU has a better chance > to keep up. So this isn't something you'd want to set in the DMA controller > driver. But I'm not sure if there is a good way to calculate a sensible > minimum buffer size based on the whole system's constraints. Not really. It's going to depend on userspace as well, and things like SMIs on systems with those. --n+lFg1Zro7sl44OB Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.20 (GNU/Linux) iQIcBAEBAgAGBQJR5RqKAAoJELSic+t+oim9l8AP/31XO0Q7swuEew4ypKwBl3Kb rJBZU13oPXRHPcQcic8gUCp3A+mDcz9onzcAWWcIlsfVmXI75mZOUmaGfU4QPVe9 GRDKNwVA+1/Rc+NA8ZqcaRTFQ1mRAAVjvmmun9mewRi2tRPze59ChQKnrYkEpafA JH2faLcdGSryLcNt4aPNnXYgemoZouSMpMmOFMqNWMViVakeIB3m1E5WXzYK8xJE nkBp5zWgesUFUKnlPiHeCcdi4gGG42kETJHWdz5ZAKVJnXa/HSLVYJUdny3csZME lqAgidLzI3h7Eh/FUCu4Xxt0jSOsfg47KoF8UBzLKokreI+kf2gf1uCD4DcLPKbN Vuvd1n8zumA7OkTAQ6ls0RgvDq+MlnP5nn/qO6bWA1WAQ/wzEDSM87b3qdrbiHL0 2b/p18VZ5hTqe8vwxh3CzrmcLWK0an/geB5WUKSfMu9V0rpXheXZJFIj84QyXMcO CdwXo2sD/gtwORKSEklcs5asfag/AfpM6C5NmI8giy+lFq+ZTmycpfvFSZzVqAny QN64ckmJxi8ZDqlOjkJSyg24knABQ2dw7sqa1m9WRlhQEajVfo6IygwX0LEDL2+g sKJ3fM7eDy93PNyafGQ5juxhCKclVm4jplT0bt+qac92T5QK4WFDMPImqgk6bcMB DwuaerzRF2iaiqfIC9EY =NmsS -----END PGP SIGNATURE----- --n+lFg1Zro7sl44OB--