From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH/RFC] mmc: add DT bindings for more MMC capability flags Date: Thu, 07 Feb 2013 01:44:22 +0100 Message-ID: <1923973.xHEn0Jh3IU@wuerfel> References: <20130206151549.GA11609@e106331-lin.cambridge.arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Return-path: Received: from moutng.kundenserver.de ([212.227.126.187]:49343 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754132Ab3BFQue (ORCPT ); Wed, 6 Feb 2013 11:50:34 -0500 In-Reply-To: Sender: linux-mmc-owner@vger.kernel.org List-Id: linux-mmc@vger.kernel.org To: Guennadi Liakhovetski Cc: Mark Rutland , "linux-mmc@vger.kernel.org" , "devicetree-discuss@lists.ozlabs.org" , Chris Ball , Magnus Damm On Wednesday 06 February 2013 17:25:42 Guennadi Liakhovetski wrote: > > Thank for pointing me out at that thread. However, I don't think > MMC_CAP_POWER_OFF_CARD has anything to do with compatibility or hardware > revisions. At least I haven't yet come across any sd/mmc hosts, that also > supply card power. You could "derive" this flag from the presence of a > regulator, capable of changing its status (switching on / off), but even > then you're not guaranteed, that you actually can (and want to) power the > card off at run-time - the regulator can be shared etc. So, an explicit > flag is needed. It sounds like something that should be handled in a controller specific way I think. E.g. on SDHCI, there seems to always be a method to power down the card using the SDHCI_POWER_CONTROL register, even without any external regulators. Arnd