On 2016/12/9 15:32, John Stultz wrote: > On Thu, Dec 8, 2016 at 11:09 PM, Chen Yu <chenyu56@xxxxxxxxxx> wrote: >> On 2016/12/9 7:29, John Youn wrote: >>> On 12/8/2016 2:43 PM, John Stultz wrote: >>>> On Tue, Dec 6, 2016 at 7:52 PM, John Youn <John.Youn@xxxxxxxxxxxx> wrote: >>>>> On 12/6/2016 5:48 PM, John Stultz wrote: >>>>>> This patch works around the issue by re-reading the GOTGCTL >>>>>> state to check if the GOTGCTL_CONID_B is still set and if not >>>>>> restarting the change status logic. >>>>> >>>>> This also seems weird. The connector id status shouldn't go back to A, >>>>> assuming you've left the cable unplugged. >>>> >>>> So I suspect this has something to do with the way the USB-A host >>>> ports on the board are wired up. As removing the usb-b plug seems to >>>> switch the device back into A mode. >>>> >>>> One quirk with this board is that the USB-A ports on the board do not >>>> function if anything is in the OTG/B plug (which is frustrating to use >>>> at times). >>>> >>> >>> Do you mean there are multiple A-ports on the board hooked up to the >>> same controller? >>> >>> If so, that would go a long way towards explaining things. Because the >>> hsotg is a single-port OTG controller. If there are multiple A-ports, >>> that means a hub has to be hard-wired internally to the port. But if >>> that's the case the OTG function won't work because OTG doesn't work >>> through a hub. It must go directly to the otg port. So there must be >>> some external logic kicking-in to switch routing to the OTG port or to >>> the HUB. >>> >>> This would explain this behavior with the ID pin status. Since hooking >>> up the HUB would make the controller an A-device whereas normally it >>> would be a B-device. >>> >>>> Guodong or Chen Yu understand the hardware details a bit better, and >>>> might be able to explain more if you need more information. >>>> >>> >>> Yeah it would be good to get some insight into this from a hardware >>> point of view. >>> >> >> Actually, I'm not very clear about the hardware details. >> >> In simple terms, there are two Type A USB 2.0 host ports and one microUSB OTG port on the front edge of the board. >> The two Type A USB 2.0 host ports connect to a high-speed hub and the hub connect to a USB Switch to which the microUSB OTG port >> also connect. >> If the Vbus of the microUSB OTG port was high or the ID of the microUSB OTG port was low, the Switch will switch the DP and DM of the SOC >> to microUSB OTG port. If no cable was inserted to microUSB OTG port, the Switch will switch the DP and DM of the SOC to the high-speed hub. >> There is another import point, the ID pin of soc will be pulled high in both cases: Sorry, I made a mistake here, the ID pin of soc will be pulled low in both cases: >> 1.no cable is inserted to microUSB OTG port >> 2.cable is inserted to microUSB OTG port and ID of microUSB OTG port is low. >> >> If my explanation confuse you, maybe these documents can be helpful. >> >> 1、https://github.com/96boards/documentation/blob/master/ConsumerEdition/HiKey/HardwareDocs/HardwareNotes.md >> >> USB Ports >> >> There are multiple USB ports on the HiKey board: >> >> One microUSB OTG port on the front edge of the board >> Two Type A USB 2.0 host ports on the front edge of the board >> One USB 2.0 host port on the high-speed expansion bus >> >> 2、https://github.com/96boards/documentation/tree/master/ConsumerEdition/HiKey/AdditionalDocs >> Hardware User Guide > > Yea, Page 12 in this pdf seems to explain it: > https://github.com/96boards/documentation/blob/master/ConsumerEdition/HiKey/AdditionalDocs/HiKey_Hardware_User_Manual_Rev0.2.pdf > > There is a usb switch which enables the micro-usb-b port if a cable is > present, or switches to using the hub(which has its own limitations > wrt multi-speed support) for the usb-a ports. > > thanks > -john > -- > 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 > > . > -- 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
