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

[Hans de Goede]

Hi,

On 12-09-16 15:56, Maxime Ripard wrote:
> 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?

Maybe the emmc needs external pull-ups ? I don't remember if u-boot
always enables those or not ...

I've not tried booting from eMMC on A33 boards (-ENOHARDWARE) but it
does work on A13 and A20 boards (last time I tried).

Regards,

Hans