From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753973AbYIWTMq (ORCPT ); Tue, 23 Sep 2008 15:12:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751553AbYIWTMi (ORCPT ); Tue, 23 Sep 2008 15:12:38 -0400 Received: from server.drzeus.cx ([85.8.24.28]:33262 "EHLO smtp.drzeus.cx" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750928AbYIWTMi (ORCPT ); Tue, 23 Sep 2008 15:12:38 -0400 Date: Tue, 23 Sep 2008 21:12:22 +0200 From: Pierre Ossman To: Haavard Skinnemoen Cc: kernel@avr32linux.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/4] atmel-mci: support multiple mmc slots Message-ID: <20080923211222.551389ab@mjolnir.drzeus.cx> In-Reply-To: <20080923201650.4525b883@hskinnemo-gx745.norway.atmel.com> References: <1222101497-21183-1-git-send-email-haavard.skinnemoen@atmel.com> <1222101497-21183-2-git-send-email-haavard.skinnemoen@atmel.com> <1222101497-21183-3-git-send-email-haavard.skinnemoen@atmel.com> <1222101497-21183-4-git-send-email-haavard.skinnemoen@atmel.com> <20080923195342.52b1164d@mjolnir.drzeus.cx> <20080923201650.4525b883@hskinnemo-gx745.norway.atmel.com> X-Mailer: Claws Mail 3.5.0cvs92 (GTK+ 2.14.0; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: multipart/signed; protocol="application/pgp-signature"; micalg=PGP-SHA1; boundary="=_freyr.drzeus.cx-23196-1222197157-0001-2" 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.drzeus.cx-23196-1222197157-0001-2 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Tue, 23 Sep 2008 20:16:50 +0200 Haavard Skinnemoen wrote: > Pierre Ossman wrote: > >=20 > > You forgot the most important part; how to handle the clock given two > > different requests. >=20 > I don't think I did. The set_ios() function merely calculates the value > of MR and stashes it away. It isn't written to the controller until > after the host has been claimed for a request. >=20 I see... It still doesn't take into account conflicting clocks. Or does the multiplexer disable the clock for the inactive slot? > > (This will also get a bit more painful when/if the core starts > > disabling the clock when a card is idle) >=20 > The atmel-mci driver already stops the clock between requests. Then I expect a patch to remove that. Fiddling with the clock is dangerous and I've seen everything from hung cards to silently broken writes when you disable the clock too early after a request. > Though I don't understand why the core would care about clocks. >=20 Power management. But it needs to be handled centrally. Primarily because of the reason above, but you might also have such things as SDIO functions requiring the clock to be on. > >=20 > > Fall back to polling? >=20 > Probably, yes. Can I fall back to polling after the host has been > registered? >=20 Hmm... no. Not sure how to handle this... Rgds --=20 -- Pierre Ossman Linux kernel, MMC maintainer http://www.kernel.org rdesktop, core developer http://www.rdesktop.org 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.drzeus.cx-23196-1222197157-0001-2 Content-Type: application/pgp-signature; name="signature.asc" Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.9 (GNU/Linux) iEYEARECAAYFAkjZP6MACgkQ7b8eESbyJLjbZACeL2CiWvLAPj8yJLMO/wljzgmC bQQAoNle8saNbo/8edwm4aqt3k7Q2hwD =JGHp -----END PGP SIGNATURE----- --=_freyr.drzeus.cx-23196-1222197157-0001-2--