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From: Fabio Tosetto <tosettofabio83@libero.it>
To: Andre Schwarz <andre.schwarz@matrix-vision.de>
Cc: linux-ppc list <linuxppc-dev@ozlabs.org>
Subject: Re: slow MMC over SPI
Date: Tue, 03 Jun 2008 07:54:30 +0200	[thread overview]
Message-ID: <4844DC96.6060807@libero.it> (raw)
In-Reply-To: <4843AD1C.4010901@matrix-vision.de>

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
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> .
>
>   

  reply	other threads:[~2008-06-03  5:54 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-06-02  8:19 slow MMC over SPI Andre Schwarz
2008-06-03  5:54 ` Fabio Tosetto [this message]
2008-06-03  7:39   ` André Schwarz

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