From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from polito.it (unknown [130.192.3.44]) by ozlabs.org (Postfix) with ESMTP id B9488DDF18 for ; Tue, 3 Jun 2008 15:54:47 +1000 (EST) Message-ID: <4844DC96.6060807@libero.it> Date: Tue, 03 Jun 2008 07:54:30 +0200 From: Fabio Tosetto MIME-Version: 1.0 To: Andre Schwarz Subject: Re: slow MMC over SPI References: <4843AD1C.4010901@matrix-vision.de> In-Reply-To: <4843AD1C.4010901@matrix-vision.de> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Cc: linux-ppc list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hello, I am trying to enable the SD over SPI on a emebedded system with one processor powerpc mpc5200b; you have enabled mmc over spi into a native spi or psc spi? regards, Fabio Andre Schwarz ha scritto: > All, > > has anybody made some investigations about performance of a SD/MMC card > on SPI ? > > Actually I'm using various cards (different speed classes) on an SPI bus > of a MPC8343 cpu. > Everything is working fine basically, i.e. card is detected properly and > block device can be mounted and used. > > SPI clock is adjusted to the card's capabilities and is running quite > fast (>30MHz). > > But between consecutive reads/writes there's a fixed gap of 2us thus > yielding a poor performance of approx. 300KBytes/sec. > The spi bus is utilized only ~10%. > > Any ideas where this comes from ? > Ist it a fixed delay regarding to some kind of spec or is it possibly a > spi driver/mmc layer issue ? > > > regards, > Andre Schwarz > > MATRIX VISION GmbH, Talstraße 16, DE-71570 Oppenweiler - Registergericht: Amtsgericht Stuttgart, HRB 271090 > Geschäftsführer: Gerhard Thullner, Werner Armingeon, Uwe Furtner > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@ozlabs.org > https://ozlabs.org/mailman/listinfo/linuxppc-dev > . > >