[U-Boot] [bug report] sunxi: booting from eMMC

[Maxime Ripard <maxime.ripard@free-electrons.com>]

Hi,

On Mon, Sep 12, 2016 at 01:53:24PM +0200, Ciprian Manea wrote:
> I'm using a SinA33 dev board (Allwinner a33 SoC) and at the moment
> I'm trying to boot from the eMMC.
> 
> But it fails in the following way:
> 
> 
> *Got the following error at boot time:*
> *U-Boot SPL 2016.09-rc2-00125-g6e8b42f (Sep 08 2016 - 11:00:46) DRAM: 1024
> MiB Trying to boot from MMC2 MMC Device 1 not found spl: could not find mmc
> device. error: -19 SPL: failed to boot from all boot devices ### ERROR ###
> Please RESET the board ###*

So I've been on the same issue for the last couple of days.

Since that board is already supported, adding support for the eMMC
basically came down to that patch on top of 2016.09-rc2.

http://code.bulix.org/kcgxri-106037?raw

(Quite hackish, the 8-Bits part being a separate issue that would need
to be addressed somehow).

However, it doesn't work, neither when flashing u-boot on the eMMC
itself (where there's a timeout error in the SPL) nor when trying to
access the eMMC from a U-Boot loaded from the (external) SD.

In the latter case, even mmc dev 1 fails silently.

I traced that down to the mmc_switch here:
http://git.denx.de/?p=u-boot.git;a=blob;f=drivers/mmc/mmc.c#l530

Which fails with ETIMEDOUT, and more specifically, it's the call to
mmc_rint_wait here
http://git.denx.de/?p=u-boot.git;a=blob;f=drivers/mmc/sunxi_mmc.c#l383
that times out.

Increasing the timeout value (to 10000) doesn't really change
anything. I guess this is also the reason why we had a timeout error
in the SPL.

This eMMC works fine in Linux, with the same muxing (and I guess the
earlier commands wouldn't be successful if the muxing or power was not
set up appropriately). So I'm kind of running out of ideas on what
could be the root cause of this.

Hans, any ideas?

Thanks,
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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