Hi again Felipe, I sent this email again without the capture because it prevented to be delivered to the mailing lists. On 04/08/2015 21:32, Felipe Balbi wrote: > On Tue, Aug 04, 2015 at 04:23:02PM +0200, Gregory CLEMENT wrote: >> Hi again, >> On 04/08/2015 15:08, Gregory CLEMENT wrote: >>> Hi Bin, >>> >>> On 02/07/2015 19:05, Bin Liu wrote: >>>> Hi, >>>> >>>> On Thu, Jul 2, 2015 at 2:16 AM, Gregory CLEMENT >>>> <gregory.clement@xxxxxxxxxxxxxxxxxx> wrote: >>>>> Hi Felipe, >>>>> >>>>> On 27/05/2015 11:42, Alexandre Belloni wrote: >>>>>> Hi, >>>>>> >>>>>> On 26/05/2015 at 09:51:18 -0500, Felipe Balbi wrote : >>>>>>> On Thu, May 14, 2015 at 04:36:33PM -0500, Bin Liu wrote: >>>>>>>> Alexandre, >>>>>>>> >>>>>>>> On Thu, May 14, 2015 at 4:26 PM, Alexandre Belloni >>>>>>>> <alexandre.belloni@xxxxxxxxxxxxxxxxxx> wrote: >>>>>>>>> On 14/05/2015 at 16:16:12 -0500, Bin Liu wrote : >>>>>>>>>> I think I found the root cause of the problem: board design issue - I >>>>>>>>>> bet the custom board has too much cap on VBUS line. It should be < >>>>>>>>>> 10uF. >>>>>>>>>> >>>>>>>>> >>>>>>>>> We have a custom board that exhibits the issue but it only has a 100nF >>>>>>>>> cap on VBUS. >>>>>>>> >>>>>>>> Have you measured the VBUS discharging? Is there any way to share your >>>>>>>> schematics? >>>>>>> >>>>>>> Alexandre, any further comments ? >>>>>>> >>>>>> >>>>>> Yeah, I have just got more info. >>>>>> >>>>>> This is the relevant part of the schematic: >>>>>> http://free-electrons.com/~alexandre/usb.png >>>>>> >>>>>> The total VBUS capacitance is 200nF and the USB0 pins are connected >>>>>> directly to the AM3358 pins. U1 is actually not fitted. >>>>>> >>>>>> We didn't measure VBUS discharging but we observe the OTG pin sensing >>>>>> stops when plugging an OTG cable without any device. >>>>> >>>>> Do you have any news about this topic? >>>>> >>>>> >>>>> Is there something else that we can do to help solving this issue? >>>> >>>> In the case of CONFIG_USB_MUSB_DUAL_ROLE=y and dr_mode=otg, how is the >>>> gadget driver configured? It has to be a module not built-in. >>> >>> Indeed when I configured CONFIG_USB_MUSB_HDRC=m and CONFIG_USB_MUSB_DSPS=m >>> it worked seamless. >>> >> >> Actually it didn't worked. And now sometimes I even received continuously >> the following message: >> >> musb_bus_suspend 2484: trying to suspend as a_wait_vfall while active > > this is likely because your VBUS hasn't dropped below 0.8V fast enough. > > I could only trigger this message in that situation. Use a scope to poke > at VBUS and see how long is takes to reach 0.8V, this could all be cause > by too much capacitance on VBUS line. We got some news: "The capacitance on VBUS due to components is 200nF and the additional parasitic capacitance will be much smaller than this" The rail discharge time is ~36ms when an USB drive is removed from the OTG adapter. I attached a capture of this. What do you think about these values? However, "there appears to be a considerable delay between the removal of a usb drive and the initiation of the VBUS discharge (maybe ~1 second, I wasn't able to measure this time)." Thanks, Gregory -- Gregory Clement, Free Electrons Kernel, drivers, real-time and embedded Linux development, consulting, training and support. http://free-electrons.com -- 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
