Re: USB_DWC3_OF_SIMPLE

[Jonathan Thibault <jonathan@navigue.com>]

Thanks for the quick reply.

On 2020-01-09 4:02 a.m., Felipe Balbi wrote:
> Hi,
>
> Jonathan Thibault <jonathan@navigue.com> writes:
>
>> Greetings,
>>
>> 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().

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?

-- 
Jonathan Thibault
Analyste/Administrateur Réseau
Navigue
97, route 132, Saint-Godefroi (Québec) G0C 3C0
581-357-2015
jonathan@navigue.com
www.navigue.com