Re: [H2200-port] MMC/SD now works on h2200

Matthew Reimer wrote:
> I just got MMC/SD working on h2200, starting from the DMA driver from the
> S3C2410 port and the opentom MMC/SD driver. I successfully mounted my ancient
> 8MB MMC card, played an MP3 from it, copied a file to it and verified its
> md5dum, and umounted it without error.
Great work!

>
> As for speed, my lame benchmark ('date; dd if=/dev/mmcblk0 of=/dev/null
> bs=16k; date'), I'm getting about 490KB/s. I'm curious how fast SD cards will
> be. The driver uses HAMCOP's DMA controller to read the data into HAMCOP's
> SRAM, and then memcpy (via dma_unmap_sg()) to its final destination, so it
> should be pretty fast. If I'm understanding the PXA/HAMCOP configuration
> correctly, it may be possible to use PXA's DMA to copy from SRAM to SDRAM;
> would that be worthwhile? I suppose it would free up the processor some.

DMA is almost always worthwhile, but I remember Pierre saying that it
won't matter much. He wrote a dma and a non-dma driver for samcop a
while ago for Freescale. He couldn't publish the sources, but he could
say dma was slightly faster.

>
> I hope to commit my patches soon, in the next day or two. (I need to remove a
> lot of junk resulting from my flailing about trying to get this working.)
>
> It should work on SAMCOP/h5400 with little modification, and I'm guessing it
> will be significantly faster than the 2.4 version.

Samcop 2.4 works at 700kb/s when debugging is disabled. It would be nice
to have > 1MB/s.

>
> Many thanks to those who answered so many basic questions, especially pb.
And many thanks to you for implementing it, of course.

regards,

Koen

>
> Matt
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Received on Sun Apr 24 2005 - 05:37:54 EDT