Re: slow MMC over SPI

Fabio,

I'm running on a MPC8343.
The SD-Card is connected on the spi hardware controller.


regards,
Andr=E9

Fabio Tosetto schrieb:

Hello,
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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=

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spi or psc spi?
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regards,
Fabio
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Andre Schwarz ha scritto:

quoted

All,

has anybody made some investigations about performance of a SD/MMC car=

d

quoted

on SPI ?

Actually I'm using various cards (different speed classes) on an SPI b=

us

quoted

of a MPC8343 cpu.
Everything is working fine basically, i.e. card is detected properly a=

nd

quoted

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

quoted

spi driver/mmc layer issue ?


regards,
Andre Schwarz

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MATRIX VISION GmbH, Talstra=DFe 16, DE-71570 Oppenweiler  - Registergeric=
ht: Amtsgericht Stuttgart, HRB 271090
Gesch=E4ftsf=FChrer: Gerhard Thullner, Werner Armingeon, Uwe Furtner