From: balbi@ti•com (Felipe Balbi)
To: linux-arm-kernel@lists•infradead.org
Subject: MUSB dual-role on AM335x behaving weirdly
Date: Tue, 18 Aug 2015 09:13:34 -0500 [thread overview]
Message-ID: <20150818141334.GC9143@saruman.tx.rr.com> (raw)
In-Reply-To: <55D326BD.2030706@free-electrons.com>
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@free-electrons•com> 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@free-electrons•com> 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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next prev parent reply other threads:[~2015-08-18 14:13 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-21 16:06 MUSB dual-role on AM335x behaving weirdly Maxime Ripard
2015-01-21 18:53 ` Bin Liu
2015-01-22 7:37 ` Yegor Yefremov
2015-01-22 10:43 ` Maxime Ripard
2015-01-22 11:01 ` Markus Pargmann
2015-01-22 14:00 ` Maxime Ripard
2015-01-22 14:52 ` Bin Liu
2015-02-05 13:21 ` Maxime Ripard
2015-02-24 10:39 ` Maxime Ripard
2015-02-24 14:54 ` Felipe Balbi
2015-02-24 16:50 ` Maxime Ripard
2015-02-24 17:33 ` Felipe Balbi
2015-02-25 11:11 ` Maxime Ripard
2015-02-25 12:11 ` Yegor Yefremov
2015-05-14 17:07 ` Felipe Balbi
2015-05-14 17:40 ` Felipe Balbi
2015-05-14 17:49 ` Felipe Balbi
2015-05-14 19:04 ` Felipe Balbi
2015-05-14 19:19 ` Bin Liu
2015-05-14 19:21 ` Felipe Balbi
2015-05-14 19:29 ` Bin Liu
2015-05-14 19:29 ` Felipe Balbi
2015-05-14 19:49 ` Felipe Balbi
2015-05-14 20:03 ` Bin Liu
2015-05-14 20:10 ` Felipe Balbi
2015-05-14 21:04 ` Bin Liu
2015-05-14 21:16 ` Bin Liu
2015-05-14 21:26 ` Alexandre Belloni
2015-05-14 21:36 ` Bin Liu
2015-05-26 14:51 ` Felipe Balbi
2015-05-27 9:42 ` Alexandre Belloni
2015-07-02 7:16 ` Gregory CLEMENT
2015-07-02 17:05 ` Bin Liu
2015-08-04 13:08 ` Gregory CLEMENT
2015-08-04 14:23 ` Gregory CLEMENT
2015-08-04 19:32 ` Felipe Balbi
2015-08-18 12:36 ` Gregory CLEMENT
2015-08-18 14:13 ` Felipe Balbi [this message]
2015-08-20 16:35 ` Gregory CLEMENT
2015-08-20 16:46 ` Felipe Balbi
2015-08-21 12:19 ` Gregory CLEMENT
2015-04-14 15:46 ` Maxime Ripard
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