From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pierre Ossman Subject: Re: Plea for MMC spec owners Date: Tue, 06 Jun 2006 00:40:01 +0200 Message-ID: <4484B2C1.6020100@drzeus.cx> References: <77C7F7CB1230A74A9D19C0C111E6EDBE41CF48@DLEE09.ent.ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <77C7F7CB1230A74A9D19C0C111E6EDBE41CF48@DLEE09.ent.ti.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-omap-open-source-bounces@linux.omap.com Errors-To: linux-omap-open-source-bounces@linux.omap.com To: "Khasim, Syed" Cc: linux-omap-open-source@linux.omap.com List-Id: linux-omap@vger.kernel.org Khasim, Syed wrote: > Hi Pierre, > > Regarding 2GB, the MMC specification doesn't state any thing clearly as > the SD spec does. > > That's too bad as I was hoping we could avoid guesswork. :-/ > As per my understanding, MMC (of all sizes) by default should be set to > operate in 512B (mandatory). This is true for both read and write. With > this default setup, I feel MMC card (<=2GB) should work as is with BLEN > set to 512. > That is my feeling as well. But it would have been nice to back it up with an official spec. > However, if the size of MMC is greater than 2GB then it switches to > sector access mode (<=2GB operates in byte access) and we are supposed > to read from EXT_CSD register for getting the density of card. I was > wondering if for some reason on some of the cards it's switching to this > mode and therefore it's not consistent across all the 2GB MMCs. > > This voodoo you speak of is rather unknown to us since we lack a real MMC4 spec. ;-) Rgds Pierre