From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752372AbZHCKei (ORCPT ); Mon, 3 Aug 2009 06:34:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751496AbZHCKeh (ORCPT ); Mon, 3 Aug 2009 06:34:37 -0400 Received: from 82-117-125-11.tcdsl.calypso.net ([82.117.125.11]:55380 "EHLO smtp.ossman.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751319AbZHCKeg (ORCPT ); Mon, 3 Aug 2009 06:34:36 -0400 Date: Mon, 3 Aug 2009 12:34:29 +0200 From: Pierre Ossman To: Matt Fleming Cc: Andrew Morton , linux-kernel@vger.kernel.org, linux-embedded@vger.kernel.org, nico@cam.org, nicolas.ferre@rfo.atmel.com, hskinnemoen@atmel.com, tony@atomide.com, david-b@pacbell.net, manuel.lauss@gmail.com, mirq-linux@rere.qmqm.pl, ppisa@pikron.com, jarkko.lavinen@nokia.com, ben@fluff.org, saschasommer@freenet.de, avorontsov@ru.mvista.com, oakad@yahoo.com, ian@mnementh.co.uk, HaraldWelte@viatech.com, JosephChan@via.com.tw, adrian.hunter@nokia.com Subject: Re: New MMC maintainer needed Message-ID: <20090803123429.390a636f@mjolnir.ossman.eu> In-Reply-To: <20090731105407.GA31900@console-pimps.org> References: <20090714153601.6dfe70ff@mjolnir.ossman.eu> <20090722151744.fffd7bf5.akpm@linux-foundation.org> <20090728222334.0c543c47@mjolnir.ossman.eu> <20090731122623.254fd0f1@mjolnir.ossman.eu> <20090731105407.GA31900@console-pimps.org> X-Mailer: Claws Mail 3.7.1 (GTK+ 2.16.2; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; protocol="application/pgp-signature"; boundary="=_freyr.ossman.eu-16264-1249295673-0001-2" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is a MIME-formatted message. If you see this text it means that your E-mail software does not support MIME-formatted messages. --=_freyr.ossman.eu-16264-1249295673-0001-2 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Fri, 31 Jul 2009 11:54:07 +0100 Matt Fleming wrote: > On Fri, Jul 31, 2009 at 12:26:23PM +0200, Pierre Ossman wrote: > >=20 > > [PATCH 0/32] mmc and omap_hsmmc patches > > http://marc.info/?t=3D124722953900010&r=3D1&w=3D2 > >=20 > > I haven't looked through these at all. The ones affecting the core > > probably need some thorough reviews. > >=20 > > I did notice the patch to say which cards a controller supports though, > > and I'm very sceptical about that one. The scanning process should work > > anyway, and the performance impact should be negligible as it is only > > on init. So that patch only adds complexity and confusion IMO. > >=20 >=20 > How much complexity does it really add? Surely it's better to give the > host controller driver writers the ability to not entertain supporting > some cards if they cannot be used? If they want to avoid the scanning > process for certain cards, why not let them? >=20 Let's look at the pros and cons of this: Con: - The scanning code gets less clear as you increase the number of possible paths through it. - Different systems will have different init sequences, possibly provoking bugs in the cards. - Host driver writers now have more capability bits they have to consider. And these might be less than obvious since SD/MMC/SDIO are normally compatible so these bits seem useless. - With the current logic (which was better in the first version), "normal" drivers will have to explicitly state that they work as intended by setting all bits. Pro: - A slightly reduced scanning time. I simply don't see it as being worth it. Linux patches generally need to provide the answer to "Why?", not just be able to avoid "Why not?". Rgds --=20 -- Pierre Ossman WARNING: This correspondence is being monitored by the Swedish government. Make sure your server uses encryption for SMTP traffic and consider using PGP for end-to-end encryption. --=_freyr.ossman.eu-16264-1249295673-0001-2 Content-Type: application/pgp-signature; name="signature.asc" Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.11 (GNU/Linux) iEYEARECAAYFAkp2vTkACgkQ7b8eESbyJLj3MwCgqr4opv7W7elnHGfgXQC5YEkz G9oAn2Up6CCouEIGRtZ8x92CJmCnSPcK =544B -----END PGP SIGNATURE----- --=_freyr.ossman.eu-16264-1249295673-0001-2--