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MMC2 booting issue on DM3730

david atkins
Intellectual 500 points


Hi,

 

I've got a custom board largely based on a cutdown beagle xm board that can boot from SD cards in MMC1 and MMC2.

 

Our goal is to be able to boot from MMC2 if it has a bootable device if not MMC1 so as to allow for upgrades, and also to allow MMC1 to be a soldered on eMMC device

We are able to boot  xload from either device if only one fitted with sys boot pins in 0b10001 state but if we have mmc1 then  it always boots from that at power on which conflcits with the docuementation, if we then do a reset pulse then it boots from mmc2

 

we also have an issue which I understand is related to the fact that mmc2 is diffrent in its dma handling to mmc1, this prevents the dvsdk build of linux from mounting the mmc2 device.

 

Anyone overcome similar issues? I have  now got an SD attached to the mmc2 of a beagle xm and behaves in the same way suggesting that the issue is with the device to my mind.

 

David

  • 0
    TI__Guru* 87550 points

    You may want to check some power or clock sequencing issue with your board.  At power up, it may be skipping over MMC2 because power to the memory is not stable yet.  By the time you do a reset pulse, power and clocks are stable and that's why it would works in that scenario.  Also ensure any transceiver or voltage translator that is in between is set up properly if that  is applicable.

    You can also check this web page for tips on MMC boot usage:  http://processors.wiki.ti.com/index.php/SD-MMC_Usage_Notes_on_OMAP35x_and_AM37x

     

    Regards,

    James

  • 0 in reply to JJD
    Intellectual 500 points

    Hi,

     

    we use same power rail for both MMC deviuces, we have also proved this happens on a Beagle XM so we know its  not hardware specific. there is no tranciever, 

     

    any other ideas?