Hi, I have just bought a WRT54Gv4 and have just installed openwrt in it, and I have been working on the SD card mod for the past few days but could not get it working.
I have tried mmc_over_gpio, with and without wireless module, with and without diag, but it is still not working.
I've tested with DD-WRT and it is working (though unstable) so I think it should not be the problem with my soldering.

dmesg output:

gpio-mmc: Failed to request mmc_spi module.
mmc_spi spi32766.0: ASSUMING 3.2-3.4 V slot power
mmc_spi spi32766.0: SD/MMC host mmc0, no DMA, no WP, no poweroff
gpio-mmc: MMC-Card "default" attached to GPIO pins di=2, do=4, clk=3, cs=7
mmc_spi spi32766.0: can't change chip-select polarity
mmc0: error -5 whilst initialising MMC card

error -5 means IO error, does that mean that other modules are using the GPIO pins as well?

Does the kernel has such mechanism such that one GPIO pin could only be assigned to one kernel module? If so then how could I check which modules used up the pins so that I could disable them?

I am a newbie in kernel module programming, reading the codes is a tough job for me, but can still manage to understand quite a bit. I've printed a lot of debugging message in the gpiommc kernel module and I think the problem is not with gpiommc, should be somewhere else but I still did not manage to find the error.

I heard that this issue is already around for a few months, wonder if anyone fixed it already, or at least find out what the problem is.
Thank you in advance.

(Last edited by chingjun on 14 Nov 2009, 17:24)