From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Subject: Re: [PATCHv10 0/5] ARM: remove the sub-node and deprecate supports-highspeed property for dwmmc. Date: Tue, 26 Aug 2014 12:19:24 +0200 Message-ID: <20140826101923.GA13619@amd> References: <1407397082-32495-1-git-send-email-jh80.chung@samsung.com> <20140825112151.GA21336@amd> <53FB1DD5.3050207@samsung.com> <20140825113719.GA31960@amd> <53FB278B.7010509@samsung.com> <53FB2807.7070503@samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:33310 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754089AbaHZKT0 (ORCPT ); Tue, 26 Aug 2014 06:19:26 -0400 Content-Disposition: inline In-Reply-To: <53FB2807.7070503@samsung.com> Sender: linux-samsung-soc-owner@vger.kernel.org List-Id: linux-samsung-soc@vger.kernel.org To: Jaehoon Chung Cc: Mark Rutland , devicetree@vger.kernel.org, Ulf Hansson , kgene.kim@samsung.com, heiko@sntech.de, tgih.jun@samsung.com, linux-mmc , Chris Ball , linux-samsung-soc@vger.kernel.org, dinguyen@altera.com, linux-arm-kernel@lists.infradead.org Hi! > >> Would you elaborate? > >> > >> If I have a device like a phone, I may want to put one "slot" inside > >> phone for basic system, and offer second slot for user expansion > >> (initially empty). > > > > if multiple slot is supported, then a mmcqd should be processing for multiple slots. > > It's too inefficient, and affect the whole performance reduction. > Sorry, Discard this comment. it means dwmci, not mmcqd. Well, that's a Linux problem, and for many applications, not even problem at all. Device tree should describe hardware, and hardware can do multiple slots per controller, so device tree should describe multiple slots per controller. Now, the configuration may be uncommon, but you are moving from good hardware description to bad hardware description. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html