[U-Boot] [PATCH] mvebu: usb: Add missing controller reset after initialization

[Stefan Roese]

On 04.01.2016 12:25, Marek Vasut wrote:
> On Monday, January 04, 2016 at 04:02:26 AM, Phil Sutter wrote:
>> Hi,
>>
>> On Mon, Jan 04, 2016 at 12:47:37AM +0100, Marek Vasut wrote:
>>> On Monday, January 04, 2016 at 12:38:07 AM, Phil Sutter wrote:
>>>> The bit which really was missing is the USB mode setting I smuggled in
>>>> along with my patch - setting the devices to host mode is sufficient
>>>> for Linux to successfully enumerate the HCD.
>>>
>>> OK, so the controller is OTG capable and upon reset, it's in Gadget mode?
>>
>> Yes, seems it's capable. Upon reset, register 0x501a0 contains value 0.
>> Trying to print register 0x511a0 freezes U-Boot for me.
>
> 0x501a0 and 0x511a0 are two different registers. Freeze usually indicates
> disabled clock to the IP block or somesuch.
>
>>>> Checking the logs of the vendor's U-Boot fork, it appears that devices
>>>> 1 and 2 are configured to host mode, while the third is set to device
>>>> mode. I changed my code to copy that, but am not sure it's necessary
>>>> at all: The DS414 exports only a single port of the SoC's EHCI, and
>>>> Linux
>>>>
>>>> detects that:
>>>> | orion-ehci f1050000.usb: EHCI Host Controller
>>>> | orion-ehci f1050000.usb: new USB bus registered, assigned bus number
>>>> | 3 orion-ehci f1050000.usb: irq 27, io mem 0xf1050000
>>>> | orion-ehci f1050000.usb: USB 2.0 started, EHCI 1.00
>>>> | hub 3-0:1.0: USB hub found
>>>> | hub 3-0:1.0: 1 port detected
>>>>
>>>> OTOH I'm not sure how far this configuration is device specific in the
>>>> first place. What puzzles me is that I couldn't find a reference to
>>>> this USB mode register at 0x501A8 in Marvell's MV78230 specs, still it
>>>> seems to be crucial. Does anyone of you have this register referenced
>>>> in some Marvell datasheet somewhere?
>>>
>>> It's the USBMODE register, see for example [1] . It's part of EHCI cores
>>> which are OTG capable.
>>>
>>> [1] http://lxr.free-electrons.com/source/drivers/usb/host/ehci-hcd.c#L179
>>
>> Interesting. I would have expected this to show up in MV78230 specs, but
>> maybe I missed the part where it clarifies these offsets to be standard
>> conformant.
>
> It seems to be standard comformant, but I didn't see the datasheet.
>
>>>> Maybe there's also a more generic way to do this, 'usb start' (which
>>>> solves the problem without any changes to the SoC init code) seems to
>>>> not address this register.
>>>
>>> Probably add a fixup into ehci-orion.c in Linux or something along those
>>> lines. It should configure the code according to the "dr_mode" DT prop.
>>
>> Hmm. Searching through the relevant DT files didn't yield a result for
>> "dr_mode". Seems like this property is missing, maybe that's why Linux
>> fails here?
>
> More likely it's not implemented for the MVEBU yet.
>
>> Is this something generally user-configurable? (Note that I
>> don't have the slightest idea of how device mode USB works in Linux).
>
> Yes, you can run the core in either Host/Gadget/OTG mode. For that to work,
> you need to configure the core mode.

I've not followed the discussion and just now going through my list
of open patches.

Phil, what is the current status of this patch? Is it still needed?

Thanks,
Stefan