Hi,

Jonathan Thibault <jonathan@navigue.com> writes:
>>> I am currently trying to port OpenWRT to Ubiquiti's EdgeRouter 4 which
>>> is a Cavium Octeon 7130.  While investigating to support XHCI (the
>>> device has a single USB3 port), I ran into the dwc3 driver which
>>> apparently supports that very chipset via the dwc3-of-simple glue.
>>>
>>> Looking at Ubiquiti's own firmware, it seems they are using a modified
>>> version of the standard xhci-platform driver.
>>>
>>> So now I am faced with two different approaches:
>>>
>>> 1- Attempt to replicate Ubiquiti's modifications to xhci-plat.
>>>
>>> 2- Switch to dwc3-of-simple.
>>>
>>> With option 1, so far, I can get xhci to load by merely adding a
>>> '.compatible =' member to usb_xhci_of_match[], but the driver complains
>>> about LPM algorithms and disables LPM (which may be fine, I don't know
>>> if it is even supported on this device).
>>>
>>> Option 2 (where you might hopefully help), potentially involves more
>>> modification to the OpenWRT since their Octeon kernel config does not
>>> appear to enable CONFIG_COMMON_CLK, which the driver depends on.  And I
>>> do not know if I should also disable standard ohci and ehci drivers once
>>> I manage to enable the USB_DWC3_OF_SIMPLE.
>>>
>>> I'm looking for recommendations on the best approach.  Keep in mind that
>>> while I can cobble together some ugly but functional hacks, I am not an
>>> experienced kernel dev.
>> Just switch to dwc3-of-simple, it already supports the SoC you're
>> dealing with. Try removing the dependency on CONFIG_COMMON_CLK. I think
>> we already get empty stubs when common clk is disabled.
>>
>> If that works for you, that's an easy patch.
>>
>
> Sadly, while it does build without the COMMON_CLK dependency, probing fails:
>
> [    4.881646] dwc3 1680000000000.xhci: Configuration mismatch. dr_mode 
> forced to host
> [    4.889574] dwc3 1690000000000.xhci: Configuration mismatch. dr_mode 
> forced to host
> [    4.897546] dwc3-of-simple: probe of 1180068000000.uctl failed with 
> error -12
> [    4.904715] dwc3-of-simple: probe of 1180069000000.uctl failed with 
> error -12
>
> The return value suggests that it's from the if(!simple->clks) check in 
> dwc3_of_simple_clk_init().

Add a check for your platform and ignore clocks altogether.

if (of_platform_is_compatible(....)) {
	ignore_clocks = true;

> The configuration mismatch warning is a bit of a mystery to me as well 
> since the only mode available in kernel config is USB_DWC3_HOST and what 
> I selected.  Would this be because the controller itself is reporting 
> another configuration?

What do you have in your Device Tree?

-- 
balbi