From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Ball Subject: Re: [PATCH 5/5] SDIO: put active devices into 1-bit mode during suspend Date: Wed, 10 Feb 2010 10:17:51 -0500 Message-ID: References: <1265747366-6676-1-git-send-email-nico@fluxnic.net> <1265747366-6676-6-git-send-email-nico@fluxnic.net> <4B7298EF.4070604@csr.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from void.printf.net ([89.145.121.20]:43808 "EHLO void.printf.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753702Ab0BJP0J (ORCPT ); Wed, 10 Feb 2010 10:26:09 -0500 In-Reply-To: <4B7298EF.4070604@csr.com> (David Vrabel's message of "Wed, 10 Feb 2010 11:30:55 +0000") Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: David Vrabel Cc: Nicolas Pitre , Andrew Morton , linux-mmc@vger.kernel.org Hi David, > Why? Is this for a specific card that doesn't support > asynchronous card interrupts while in 4-bit mode? If so, I'd > suggest a card quirk for this and only switch modes for these > cards. (As a check that we're on the same page -- sdio_disable_wide() is only called if MMC_PM_KEEP_POWER is true, which means the system is going to be suspended but the card will remain externally powered without its clock.) Under the circumstances above, it's a requirement of the SDIO spec that moving to 1-bit mode must happen before stopping the clock if the interrupt mechanism is to be used to wake the host, and the chipset we've been using (Via VX855) fails to generate a wakeup if the switch isn't made. Do you have experience of another chipset that doesn't need the switch to 1-bit mode for a clockless wakeup? Thanks, - Chris. -- Chris Ball One Laptop Per Child