[U-Boot] USB Device Identification -- non-removable USB NAND flash

[Albert ARIBAUD <albert.u.boot@aribaud.net>]

Hi Curt,

On Wed, 17 Apr 2013 21:33:29 -0700 (PDT), Curt Brune
<curt@cumulusnetworks.com> wrote:

> Hi - 
> 
> Looking for suggestions on how to identify a particular USB mass storage device on my platform.
> 
> My platform has a P2020 SoC.  The SoC USB controller is connected to an on board USB hub.  The hub has 3 connections as follows:
> 
> +---------+
> |         |--->[USB flash controller, fronting a 2GB NAND flash]
> | USB Hub |--->[front panel USB connector]
> |         |--->[front panel USB connector]
> +---------+
> 
> My uImage is stored on the NAND in a raw partition. I have been using the usbboot command just fine.  Something like this:
> 
>   uboot> usbboot $loadaddr 0:0 && bootm $loadaddr
> 
> That boots from storage device 0, partition 0.  That works great.
> 
> The problem is when I *also* have a USB memory stick plugged into one of the front panel ports.  In that case my boot device no longer shows up as device "0", but rather "1".
> 
> I'm guessing this problem is not unique.
> 
> Is there a way to "fix" the device number for the non-removable flash to always be 0?
> 
> Alternatively is there a way to figure out at run time (in a script) what device corresponds to my internal flash?
> 
> I started hacking on common/usb.c and I see how I can make it work, but that solution seemed wrong.  There's got to be a better way.
> 
> Any suggestions are much appreciated.

Haven't tested this at all, but maybe first do a "usb dev 1" and test
if it succeeded (probably requires enabling the HUSH parser), and if
it did, (try to) load from it; otherwise fall back to "usb dev 0" and
(try to) load.

Testing could actually be "blank a memory area, select usb dev 1 and
blindly load the boot image to the memory area, test image with
'iminfo', and decide if you go on or switch to dev 0.

> Cheers,
> Curt

Amicalement,
-- 
Albert.