Return-path: Received: from mail-ww0-f42.google.com ([74.125.82.42]:60070 "EHLO mail-ww0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750868Ab0GYMk5 (ORCPT ); Sun, 25 Jul 2010 08:40:57 -0400 MIME-Version: 1.0 In-Reply-To: <4C482D01.1040109@nokia.com> References: <1279733634-21974-1-git-send-email-ohad@wizery.com> <1279733634-21974-19-git-send-email-ohad@wizery.com> <4C482D01.1040109@nokia.com> From: Ohad Ben-Cohen Date: Sun, 25 Jul 2010 15:40:35 +0300 Message-ID: Subject: Re: [PATCH v2 18/20] mmc: sdio: enable a default power off mode of the card To: Roger Quadros Cc: "linux-wireless@vger.kernel.org" , "linux-mmc@vger.kernel.org" , "linux-omap@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux@arm.linux.org.uk" , Chikkature Rajashekar Madhusudhan , "Coelho Luciano (Nokia-MS/Helsinki)" , "akpm@linux-foundation.org" , San Mehat , Tony Lindgren , Nicolas Pitre , Pandita Vikram , Kalle Valo Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-wireless-owner@vger.kernel.org List-ID: On Thu, Jul 22, 2010 at 2:35 PM, Roger Quadros wrote: > On 07/21/2010 08:33 PM, ext Ohad Ben-Cohen wrote: >> >> Add support for an SDIO device to stay powered off even without >> the presence of an SDIO function driver. A host should explicitly >> ask for it by means of MMC_CAP_DONT_POWER_CARD, and the SDIO >> function driver should know it needs to call sdio_claim_power >> before accessing the device. >> >> Signed-off-by: Ohad Ben-Cohen > > Shouldn't this be the default behaviour? If there is no function driver for > any of the functions of the card, then sdio core shold power off the card. > > I don't see a need for a special capability flag for this. > > in fact MMC_CAP_DONT_POWER_CARD does not seem like an mmc host's capability Totally agree. I didn't want to change the current behavior of the cards/funcs so I looked for a way to explicitly power down only specific cards. Alternatively we could power down all cards at the end mmc_attach_sdio, and then power them up selectively in sdio_bus_probe, just before calling probe. If the probe succeeds, the function driver takes over. If the probe fails, we can power them down again. Is that what you meant ? This would work both if the sdio function driver is already loaded, or will only be loaded at a later time. But I'm not too fond of the extra power on/off cycles that it will introduce for each card.. Thanks, Ohad. > flag, it seems more like a request from the board to keep the card powered > off. > > regards, > -roger >