On 07/29/2013 07:26 PM, Bin Liu wrote: > Sebastian, Hi Bin, > I did not say AM335xEVM is not able to run OTG mode. The problem is in > OTG mode the SESSION bit will be cleared once the device is unplugged, > then there is no way the SESSION bit will come back in the current > mainline kernel. Yes, you did. > > The TI 3.2 kernel works around this OTG issue by toggling the SESSION > bit in b_idle handling in otg_timer(). The workaround makes most users > happy but it causes VBUS voltage pulsing. That is why I said I don't > know an ideal solution without a ID pin interrupt support. Now I understand more pieces of the puzzle. And the missing ID pin support is Am335x-evm specific since other am335x board may wire up that pin. But you say there is no way that the phy or anything else could help to avoid that pulsing. > I think you looked at a wrong file, maybe a wrong branch. Please check > [1], which defines > > 2644 * mode[0:3] = USB0PORT's mode > 2645 * mode[4:7] = USB1PORT's mode > 2646 * AM335X beta EVM has USB0 in OTG mode and USB1 in host mode. > 2647 */ > 2648 .mode = (MUSB_HOST << 4) | MUSB_OTG, Oh it is a long way. So looked into the wrong branch. >> I agree that without that try_idle part things keep working but it >> seems, that it is also called in the other tree. >> > > Then because AM335xEVM USB1 port does not call *try_idle() in this 3.2 > kernel, its SESSION bit is always set. > > But I don't have a clear idea how to solve this in the mainline kernel > since is_otg_enabled() has been cleaned. So now I think this is a board problem. What about switching port 1 from OTG to HOST only and avoiding kicking the timer in dsps_musb_try_idle() in such a case? It seems we only need to do this in OTG mode. > Regards, > -Bin. Sebastian -- 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
