[U-Boot] USB works (or not) depending on SYS_BOOT (with TPS65920)

[Jason Kridner]

On Tue, Aug 9, 2011 at 2:25 PM, Jason Kridner <jkridner at beagleboard.org> wrote:
> On Tue, Aug 9, 2011 at 4:21 AM, Orjan Friberg <of at flatfrog.com> wrote:
>> On 2011-07-07 14:27, Orjan Friberg wrote:
>>> On 2011-07-07 11:37, Orjan Friberg wrote:
>>>> It seems the boot rom must be doing some initialization of the USB phy
>>>> (this is with a TPS65920).
>
> It does.  The BeagleBoard-xM uses a TPS65950, but I don't know if that
> matters.  The ROM code does send some commands across the I2C bus.
> You might grab yourself an I2C bus monitor to make it easy to see
> what.
>
>>>
>>> I forgot to add that I'm using a configuration header and not x-loader
>>> as the 1st stage bootloader.
>>>
>>> On a BeagleBoard xM (with x-loader), usb reset works fine coming out of
>>> a cold reset.
>>>
>>> I'd better check my configuration header.
>>
>> Ok, so I've booted a u-boot with a configuration header on the xM board
>> and 'usb reset' works fine after a cold boot.  Vice versa, using
>> x-loader + u-boot on our own board, 'usb reset' does not work.
>>
>> I'm looking at the silicon erratas for the 3730 and the TPS chip and
>> found a couple of entries relating to the OTG functionality.  However,
>> they don't correlate with silicon revision differences between the xM
>> board and our own board (and they don't seem to apply here).
>>
>> What other stuff should I be looking into?  (The xM board uses a 65950
>> whereas we are using the 65920, but the errata is for all 659x0 devices.)
>
> I'd carefully check that you are powering up all the critical rails
> for USB to work.  You can take a look at the USB PHY initialization in
> the kernel [2].  Is the OTG functionality working for you when you
> boot into Linux?  Are these initialization steps part of the setup for
> your board?

[2] http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=blob;f=drivers/usb/otg/usb/otg/twl4030-usb.c;h=14f66c35862938adc5817c123233521c9ca1f925;hb=HEAD#l531

>
> Might have been good to CC the x-loader and beagleboard lists.  I see
> you checked on the e2e.ti.com list at [1].  That's good.
>
> You might want to try using the latest u-boot, since you seem to
> indicate you are using an old version.
>
>>
>> The 3730 TRM talks about the boot ROM doing USB PHY initialization, but
>> it doesn't list any details.
>
> You might be able to get details somewhere, but I suspect you'll get
> the I2C bus capture first.
>
>>
>> Thanks for any suggestions,
>>
>> Orjan
>>
>> --
>> Orjan Friberg
>> FlatFrog Laboratories AB
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>>
>
> [1] http://e2e.ti.com/support/dsp/omap_applications_processors/f/447/p/120937/454647.aspx
>