On Tue, Apr 8, 2008 at 12:05 AM, David Brownell <david-b@xxxxxxxxxxx> wrote: > On Monday 07 April 2008, Felipe Balbi wrote: > > I recall having some issues on 100mA devices. During enumeration some > > current spikes a few mAs above 100mA were occuring and we couldn't > > enumerate the device due to vbus_err interrupt. > > Yeah, I think the Mentor core is unduly sensitive to voltage > fluctuation during enumeration. There's supposed to be about > 100 msec before VBUS must stabilize ... but the silicon doesn't > seem to accept routine instabilities in that period, and then > reports inappropriate VBUS errors. > For this VBUS error, Blackfin MUSB port follows other platforms idea to retry. But to this bug, the ZiO card reader will trigger the mode change maybe due to the VBUS drop. It should be different as the VBUS error in the enumeration, because the enumeration of the ZiO is OK. And for our development board EZKIT548, it can provide 500mA current at 5V as it claimed in manual with a external regular. So from my point of view, this bug is not related with 100mA current limit issue. > > > > If you check drivers/usb/musb/tusb6010.c you'll see that we've > > implemented a retry condition for those cases. The same retry can > > be found in musb_core.c > > The DaVinci support needed the same kind of logic. All in > all this is painful stuff to sort out, and it seems that > each platform rediscovers it. It would be better if the > silicon itself weren't fighting back so hard... > Yes, I reported this to our silicon designers. -Bryan -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
