* Felipe Balbi <balbi@xxxxxx> [130515 07:11]: > On Fri, May 03, 2013 at 11:01:33AM -0700, Tony Lindgren wrote: > > * Tony Lindgren <tony@xxxxxxxxxxx> [130503 10:55]: > > > Looks like we can get VBUS interrupt before the ID interrupt > > how can this happen ? VBUS interrupt happens when you connect to a port > which is sourcing VBUS to you, while ID interrupt happens when ID is > grounded, meaning that you should be sourcing VBUS. Yes, in this case we get both interrupts and the order depends on how fast/slow the cable is inserted. > Have you hacked a Hub to backfeed 5V to OMAP by any chance ? ..as that's how the LapDock seems to behave backfeeding 5V. It would be interesting to take a look at the signaling on it, but I think my old beagle sniffer is fried. Looking at the "Figure 6-1: Common State Diagram" on page 32 in "USB_OTG_and_EH_3-0_release_1_1_10May2012.pdf" the logic is the following depending on the order of interrupt: start -> id ground -> a_idle -> a_wait_vrise -> a_wait_bcon... or start -> vbus -> b_idle -> id ground -> a_idle -> a_wait_vrise -> a_wait_bcon... I don't think having the VBUS there actually violates that if we just should follow the ID state and accept that a_wait_vrise is already satisfied and not even try to turn the VBUS at MUSB end in that case. Regards, Tony -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
