eMMC v5.1

Peter Steinberg

Other Parts Discussed in Thread: AM3352, CSD

Our device is using an AM3352 with the Linux imaged based on the files in ti-processor-sdk-linux-am335x-evm-01.00.00.00-Linux-x86-Install.bin.

We need to replace the eMMC chip and the kernel fails to recognize the new chip.

I've traced it down to the fact the new eMMC chip uses MMC v5.1, so it reports a EXT_CSD_REV of 8.

The code in drivers/mmc/core/mmc.c, function mmc_read_ext_csd, has a block that fails if EXT_CSD_REV is greater than 7.

if (card->ext_csd.rev > 7) {
  pr_err("%s: unrecognised EXT_CSD revision %d\n",
    mmc_hostname(card->host), card->ext_csd.rev);
  err = -EINVAL;
  goto out;
}

Later version of the SDK have this block removed (as well as other changes).

I don't want to move to a newer version of the SDK / kernel if at all possible.

Can I just delete this block without any other changes to support the newer eMMC chip, do I need to port in a newer version of the entire MMC driver, or do I have to move to a newer kernel / SDK?

Thanks,

Peter Steinberg

over 8 years ago

0 Titusrathinaraj Stalin over 8 years ago

TI__Guru** 116100 points

Can you please try any one of the below code and check ?

if (card->ext_csd.rev > 8) {
pr_err("%s: unrecognised EXT_CSD revision %d\n",
mmc_hostname(card->host), card->ext_csd.rev);
err = -EINVAL;
goto out;
}

OR

if (card->ext_csd.rev > 9) {
pr_err("%s: unrecognised EXT_CSD revision %d\n",
mmc_hostname(card->host), card->ext_csd.rev);
err = -EINVAL;
goto out;
}

0 Peter Steinberg over 8 years ago in reply to Titusrathinaraj Stalin

Expert 1640 points

I just commented out that block and it appears to work properly.

It takes time to do extensive testing, so I'm asking if there are any side effects that I should focus the testing on.

I really don't want to switch to the V3.00 Linux SDK unless I am forced to. That would require extensive changes to our codebase and the corresponding testing.

Thanks,

Peter

0 Titusrathinaraj Stalin over 8 years ago in reply to Peter Steinberg

TI__Guru** 116100 points

I have also changed this things and worked for me, that's why I suggested you to do.
That time, I referred the mainline kernel and didn't see that csd revision failure case so I used it.

git.kernel.org/.../mmc.c
I hope, you won't get any issues due to this change.

0 Peter Steinberg over 8 years ago in reply to Titusrathinaraj Stalin

Expert 1640 points

Thanks.

0 Diego Santa Cruz over 8 years ago in reply to Peter Steinberg

Intellectual 360 points

For info, this was fixed in the mainline kernel in the following two commits:

6636bad839d9 mmc: core: Update the ext-csd.rev check for eMMC5.0
03a59437ef6b mmc: Allow forward compatibility for eMMC

0 Titusrathinaraj Stalin over 8 years ago in reply to Diego Santa Cruz

TI__Guru** 116100 points

Thanks Diego.

Because of the holidays, TI E2E™ design support forum responses will be delayed from Dec. 25 through Jan. 2. Thank you for your patience.

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eMMC v5.1