Re: [PATCH v3] mmc: mxs-mmc: add mmc host driver for i.MX23/28

Wolfram Sang
2011-02-22T10:33:51Z

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> > What throughput rates do you get on a mx28-regulated slot serving a card
> > at 50Mhz? This is poor here (55kb/s) while it is OK at 25Mhz. Could be a
>
> To make sure we are on the same test, can you share the test case
> you ran to get the result? So that I can run it here for the result
> on my board.

# mount -t vfat /dev/mmcblk0p1 /mnt
# dd if=/mnt/test.dat of=/tmp/a bs=1024
# umount /mnt
# ./dd --version
dd (coreutils) 8.5
...

'test.dat' was a 8MB file of random data on a 4GB SDHC card
(extrememory) on a slot powered by the mx28. Operating the card at
50Mhz, dd will report ~55 kb/s. If I add 'rate /= 2;' to the beginning
of set_clk_rate, so it will operate at 25Mhz, I have 8mb/s.

Regards,

Wolfram

--
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Industrial Linux Solutions | http://www.pengutronix.de/ |

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