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

[Lubomir Popov]

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