[U-Boot] [PATCH] ARM: tegra: TrimSlice: add support for USB1 port

[Stephen Warren <swarren@wwwdotorg.org>]

On 11/02/2012 09:30 AM, Lucas Stach wrote:
> Am Freitag, den 02.11.2012, 08:45 -0600 schrieb Stephen Warren:
>> On 11/01/2012 05:34 PM, Lucas Stach wrote:
>>> Am Donnerstag, den 01.11.2012, 17:30 -0600 schrieb Stephen Warren:
>>>> On 11/01/2012 05:17 PM, Lucas Stach wrote:
>>>>> Hi Stephen,
>>>>>
>>>>> Am Donnerstag, den 01.11.2012, 16:14 -0600 schrieb Stephen Warren:
>>>>>> From: Stephen Warren <swarren@nvidia.com>
>>>>>>
>>>>>> TrimSlice's USB1 port has two purposes; it either acts as a device port
>>>>>> hosting Tegra's USB recovery protocol, or acts as a host port connected
>>>>>> to the internal USB->SATA bridge chip, which may in turn be connected to
>>>>>> an SSD or HDD. Add the appropriate device tree and board configuration
>>>>>> options to enable this port as a host port, and route the port to the
>>>>>> SATA bridge using the VBUS GPIO.
>>>>>>
>>>>> Hm, I don't really like to abuse the VBUS GPIO for this function. As the
>>>>> GPIO controlled routing is more a sort of pinmux can't you just add the
>>>>> GPIO enable to pin_mux_usb()?
>>>>
>>>> I don't know, I think it's fine. It's certainly this way in the kernel.
>>>> And for all I know, this GPIO does actually affect VBUS as well as
>>>> flipping any mux (and the more I think about that, the more likely it
>>>> is) although I can't actually know for sure since I don't have the
>>>> schematics.
>>>
>>> If it's really triggering VBUS I'm fine with this, but then the comment
>>> in pin_mux_usb() is a bit off.
>>
>> Sorry, I don't see anything inaccurate about it. What's wrong?
>
> In which way is it "masquerades as a VBUS GPIO"? If it triggers VBUS it
> _is_ a VBUS GPIO. So the comment should rather state that switching on
> VBUS also muxes the port to the internal bridge.

The GPIO definitely flips some form of bus mux. It's unclear whether it
is a also VBUS GPIO for the internal device or not. My suspicion is that
it must be, but without schematics I can't confirm. Either way, the
comment seems quite accurate and descriptive, and this seems a perfectly
reasonable solution.