[U-Boot] MXC: Performance issue/glitch with reading/writing files from SD card

[U-Boot] MXC: Performance issue/glitch with reading/writing files from SD card

[alfred steele]

Hi,

Looks like there is a huge performance issue with the sdhc
hardware/software driver on the mx31
Earlier on i had adapated the freescale mx "sdhc driver" and ported it
to the mx31 platform for U-boot v1.0. I have modified the driver to
put the host as well as the card in 4 bit mode in the initialization
sequence.
Inspite of that doing a "fatload" for a file of size of the order of
16MB takes about 10 minutes, which is nowhere near the theoretical
speed  even in 1 bit mode.   I have seen the scope trace(s) and looks
like multiple Data pins are being used for data, but seems like it
takes forever, Could anyone give me quick clues as to what could be
the issue?
I haven't done any measure on the linux side yet using "dd".

Thanks in advance,
Alfred

[U-Boot] MXC: Performance issue/glitch with reading/writing files from SD card

[Stefano Babic]

alfred steele wrote:
> Hi,
> 
> Looks like there is a huge performance issue with the sdhc
> hardware/software driver on the mx31

Actually I do not find any MX31 board in the mainline supporting MMC.
However, drivers/mmmc/mxcmmc.c is suitable for both MX2 and MX3 processors.

> Earlier on i had adapated the freescale mx "sdhc driver" and ported it
> to the mx31 platform for U-boot v1.0. I have modified the driver to
> put the host as well as the card in 4 bit mode in the initialization
> sequence.

This is your code and I am afraid we cannot help you. And u-boot 1.0
belongs to prehistory. I can only suggest you to update to the actual
u-boot (2010.06-rc3) and sets your target to use the mxcmmc driver, and
reports us if you find problems.

Best regards,
Stefano Babic

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