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

[Marek Vasut]

Dear Dan Murphy,

> 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?

Nice to see this is moving in some well-defined direction.

Best regards,
Marek Vasut