From mboxrd@z Thu Jan 1 00:00:00 1970 From: binmlist@gmail.com (Bin Liu) Date: Thu, 14 May 2015 16:36:33 -0500 Subject: MUSB dual-role on AM335x behaving weirdly In-Reply-To: <20150514212653.GC3338@piout.net> References: <20150514170700.GN24269@saruman.tx.rr.com> <20150514174031.GP24269@saruman.tx.rr.com> <20150514174907.GQ24269@saruman.tx.rr.com> <20150514190429.GT24269@saruman.tx.rr.com> <20150514192125.GU24269@saruman.tx.rr.com> <20150514192946.GV24269@saruman.tx.rr.com> <20150514212653.GC3338@piout.net> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Alexandre, On Thu, May 14, 2015 at 4:26 PM, Alexandre Belloni 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? Regards, -Bin. > >> I just noticed I have the Jumper 36 on on my EVM, which adds 154.7uF >> cap on VBUS causing discharge takes ~20sec. After removed the jumper, >> which leaves only 4.7uF cap on VBUS, now it only takes ~0.4sec to >> generate Disconnect IRQ. Here is the log. >> >> root@:~# [ 2504.893123] musb-hdrc musb-hdrc.0.auto: usbintr (1) epintr(0) >> [ 2504.899198] musb-hdrc musb-hdrc.0.auto: <== DevCtl=99, int_usb=0x1 >> [ 2504.912751] zero gadget: suspend >> [ 2504.916145] zero gadget: zero_suspend >> [ 2505.303937] musb-hdrc musb-hdrc.0.auto: usbintr (20) epintr(0) >> [ 2505.310072] musb-hdrc musb-hdrc.0.auto: <== DevCtl=88, int_usb=0x20 >> [ 2505.325355] zero gadget: reset config >> [ 2507.303288] musb-hdrc musb-hdrc.0.auto: Poll devctl 80 (b_idle) >> > > -- > Alexandre Belloni, Free Electrons > Embedded Linux, Kernel and Android engineering > http://free-electrons.com