[U-Boot] [U-Boot, v3, 6/7] USB: usb-hub: Add a weak function for resetting devices

[Lubomir Popov]

Hi Dan,

On 26/07/13 03:30, Dan Murphy wrote:
> Lubo
> 
> Thanks for the reply
> 
> On 07/25/2013 03:38 PM, Lubomir Popov wrote:
>> Hi Dan, guys,
>>
>> Just would like to give my 5 cents: my humble experience with
>> OMAP4 and OMAP5 tells me that this (that is, the need to reset
>> devices after applying port power) seems to be a OMAP5 HSIC IP
>> issue, and not a device problem. We at MMS have two custom
>> designs, one with OMAP5430 and one with OMAP4460, both of which
>> employ HSIC chips (LAN9730 and USB4640 on the OMAP5 board, and
>> USB4640 on the OMAP4), along with a ULPI PHY (TUSB1210) on both
>> boards. I had the pleasure of bringing up both boards with U-Boot
>> a few months back, including USB EHCI, and can state the
>> following:
>>
>> Device reset after port power is applied is needed for the OMAP5
>> HSIC devices only. The ULPI PHY on both boards doesn't even have
>> a hardware reset connected, nevertheless the device attached to
>> it gets enumerated (even without performing PHY software reset
>> via the ULPI viewport). I performed the HSIC device reset by
>> calling a board function from within the ehci_hcd.c driver, which
>> is compiled only for the OMAP5, and only if we have HSIC devices.
>> An obsolete patch for this, working on my board, can still be found
>> at http://patchwork.ozlabs.org/patch/232742/, as well as a RFC for
>> the 5432uevm (untested) at http://patchwork.ozlabs.org/patch/244124/
>>
>> On the OMAP4 board this reset is not needed, the HSIC device gets
>> enumerated straightforward.
>>
>> I don't know about other arches, but I'm not sure that having an
>> unconditional common call, although weak, in usb_hub.c is the best
>> solution.
>>
>> Best regards,
>> Lubo
>>
>>
> I see your patches and see that you have added a omap5 specific call to reset the device in the ehci-hcd.c.
> 
> I originally had a similar implementation in ehci-hcd but decided to move it up to the usb-hub.  http://patchwork.ozlabs.org/patch/258229/
> 
> But I can move it back since the patch exists.
> 
> This make it all board specific because as you point out it is only needed in HSIC connection
> 
> Crazy question was there any support documentation for the OMAP5 HSIC issue?
Well, none that I know of. Apart from the published HSIC bug (errata ID i774),
which however seems unrelated to this particular issue, I'm not aware of any
other documented problems. But I must admit that I'm not a TI employee anymore
(my xID has expired in April) and at present don't have access to TI's internal
stuff, so my info could be obsolete.

You could try to contact Jerome Angeloni <j-angeloni at ti.com>, if he still has
the TI account active - he was the guy at TI France with most experience with
OMAP USB applications. But, as you know, TIF is gone...
> 
> Dan
> 
> -- 
> ------------------
> Dan Murphy
> 
Regards,
Lubo