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 Post subject: SD card in linux on at91sam9g20
PostPosted: Tue Jun 07, 2011 4:37 pm 
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Joined: Tue Jun 07, 2011 4:22 pm
Posts: 2
Hello,

I'm trying to port linux on a custom board with at91sam9g20 processor. I successfully compiled and installed u-Boot (2011.03) and linux kernel 2.6.38 with patches from at91 maintainer. I'd like to have rootfs on an sd card which is connected to the slot_a of the at91 mci controller. Unfortunately I was not able to make sd working during last 4 days, I have limited possibility of debugging (no JTAG) so I only discovered that probing for sd card during the boot hangs up waiting for some response (functions mmc_rescan_try_freq -> mmc_send_if_cond ...). It should not be a hardware issue because on the same desk sd card works on bare metal application.

I also tried the same configuration of kernel (with only difference in slower processor at91sam9260 and sd card on slot_b) on at91sam9260ek development board, where sd card works fine.

Have anyone been solving similar problem, please?
(I can post more details, if needed...)

regards
Jan


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 Post subject: Re: SD card in linux on at91sam9g20
PostPosted: Wed Jun 08, 2011 11:48 am 
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Joined: Tue Jun 07, 2011 4:22 pm
Posts: 2
The issue is (partially) solved. There was a problem with driver loading order - sd card driver was not loaded at the time of mounting the rootfs. I have solved it by loading it with
subsys_initcall(at91_mci_init); instead of module_init(at91_mci_init); I'm not sure how "ugly" this hack is, but now it works as I need.
The weird thing is, that this hack is not needed on the at91sam9260ek board.

regards
Jan


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