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However, no mechanism to guarantee this ordering >>> was implemented, and currently, in the general case, the configuration >>> functions tegra_xhci_id_work() and tegra_xudc_usb_role_sw_work() end up >>> running in the same order regardless of the transition being HOST- >>> >DEVICE >>> or DEVICE->HOST, leading to one of these transitions ending up in a >>> non-working state due to the new configuration being clobbered by the >>> previous controller driver setting USB_ROLE_NONE after the fact. >>> >>> Fix this by introducing a helper that waits for the USB2 port’s current >>> role to become USB_ROLE_NONE and add it in the configuration functions >>> above before setting the role to either USB_ROLE_HOST or >>> USB_ROLE_DEVICE. The specific parameters of the helper function are >>> choices that seem reasonable in my testing and have no other basis. >> >> This is no information here about why 6 * 50/60us is deemed to be >> sufficient? May be it is, but a comment would be nice. > > I missed this review comment and I'm not sure what you mean here. Do you > want me to comment on the commit message on how I chose these > parameters? If so it's as stated in the current message, I simply tested > with these parameters and it worked and I really have no better basis > for choosing them. If you mean adding a comment in the code I can do > that for v2. Yes please be explicit about how you arrived at these numbers. Ie. based upon your testing on what platform, etc. Thanks Jon -- nvpublic