From mboxrd@z Thu Jan 1 00:00:00 1970 From: Russell King - ARM Linux Subject: Re: [PATCH] mmc: mmci: Improve runtime PM support Date: Mon, 24 Oct 2011 10:42:03 +0100 Message-ID: <20111024094203.GI9893@n2100.arm.linux.org.uk> References: <1319210754-22775-1-git-send-email-ulf.hansson@stericsson.com> <20111021173637.GG21648@n2100.arm.linux.org.uk> <4EA51C4A.7040802@stericsson.com> <20111024090432.GA9893@n2100.arm.linux.org.uk> <4EA53181.2050700@stericsson.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from caramon.arm.linux.org.uk ([78.32.30.218]:58516 "EHLO caramon.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753966Ab1JXJmV (ORCPT ); Mon, 24 Oct 2011 05:42:21 -0400 Content-Disposition: inline In-Reply-To: <4EA53181.2050700@stericsson.com> Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Ulf Hansson Cc: Sebastian Rasmussen , "linux-mmc@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , Lee Jones On Mon, Oct 24, 2011 at 11:36:01AM +0200, Ulf Hansson wrote: > Russell King - ARM Linux wrote: >> I repeat: if you cut power to the card, you have to re-initialize it. >> Re-initialization takes quite a bit of time to re-detect and setup >> the card. You'd also need to re-configure things like the transfer >> mode and so forth. > > Right now host->vcc (vmmc) regulator is controlling the power to card. > Not the MCIPWR register! Maybe for you, but that's not the case on all platforms. You *really* need to get out of the idea that just because your implementation works one way that everything works that way. You're working on a cross-SoC cross-platform driver, and you need to take account of how other platforms work. In that case, there *are* platforms which the MCIPWR register does indeed control power to the card - and setting this to zero _will_ power down the card. > I would be very surprised if any hardware has this kind of setup, that > the PL180 itself controls a regulator. ARM dev boards all use the MCIPWR bits to control an external power switch - there's no adjustment of the voltage except via soldered links on the board.