slow MMC over SPI

slow MMC over SPI

[Andre Schwarz]

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

Re: slow MMC over SPI

[Fabio Tosetto]

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
> .
>
>   

Re: slow MMC over SPI

[André Schwarz]

Fabio,

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


regards,
Andr=E9

Fabio Tosetto schrieb:
> Hello,
>=20
> 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=
=20
> spi or psc spi?
>=20
> regards,
> Fabio
>=20
> Andre Schwarz ha scritto:
>> All,
>>
>> has anybody made some investigations about performance of a SD/MMC car=
d
>> on SPI ?
>>
>> Actually I'm using various cards (different speed classes) on an SPI b=
us
>> of a MPC8343 cpu.
>> Everything is working fine basically, i.e. card is detected properly a=
nd
>> 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, Talstra=DFe 16, DE-71570 Oppenweiler  -=20
>> Registergericht: Amtsgericht Stuttgart, HRB 271090
>> Gesch=E4ftsf=FChrer: Gerhard Thullner, Werner Armingeon, Uwe Furtner
>> _______________________________________________
>> Linuxppc-dev mailing list
>> Linuxppc-dev@ozlabs.org
>> https://ozlabs.org/mailman/listinfo/linuxppc-dev
>> .
>>
>>  =20
>=20


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