Hi, On Tue, Aug 18, 2015 at 02:36:13PM +0200, Gregory CLEMENT wrote: > 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)." yeah, this is really weird. I can't think of anything that would make VBUS discharge slower from a SW point of view. Once you remove the cable, VBUS is physically removed and there's nothing else charging it. -- balbi
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