From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Ball Subject: Re: Stopping mmc clock between transfers Date: Wed, 25 May 2011 11:54:53 -0400 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from void.printf.net ([89.145.121.20]:51731 "EHLO void.printf.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757978Ab1EYPxi convert rfc822-to-8bit (ORCPT ); Wed, 25 May 2011 11:53:38 -0400 In-Reply-To: (=?utf-8?Q?=22Marc-Andr=C3=A9=09H=C3=A9bert=22's?= message of "Tue, 24 May 2011 14:42:32 -0400") Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: =?utf-8?Q?Marc-Andr=C3=A9_H=C3=A9bert?= Cc: linux-mmc Hi Marc-Andr=C3=A9, On Tue, May 24 2011, Marc-Andr=C3=A9 H=C3=A9bert wrote: > We are using a OMAPL108 with 2.6.33 and noticed that the mmc clock > signal stays active when idle. This doesn't seem very power efficient > and we wondered if there was a reason for this. Before trying to fix > this on our side I had a few questions regarding this: > -Is this behavior the same in more recent versions? > -Was this designed to be this way? > -Would stopping the clock be a responsibility of the core (set_ios) o= r > the host controller (between requests)? Check out CONFIG_MMC_CLKGATE=3Dy, introduced in 2.6.38. - Chris. --=20 Chris Ball One Laptop Per Child