> From: linux-usb-owner@xxxxxxxxxxxxxxx [mailto:linux-usb-owner@xxxxxxxxxxxxxxx] On Behalf Of Alan Stern > Sent: Wednesday, June 04, 2014 6:57 AM > > On Wed, 4 Jun 2014, Yang,Wei wrote: > > > On 06/04/2014 09:45 AM, Peter Chen wrote: > > > > > >> commit d18f7116a5ddb8263fe62b05ad63e5ceb5875791 > > >> Author: Robert Baldyga <r.baldyga@xxxxxxxxxxx> > > >> Date: Thu Nov 21 13:49:18 2013 +0100 > > >> > > >> usb: gadget: s3c-hsotg: fix disconnect handling > > >> > > >> This patch moves s3c_hsotg_disconnect function call from USBSusp > > >> interrupt > > >> handler to SET_ADDRESS request handler. > > >> > > > It is a little strange we call gadget's disconnect at SET_ADDRESS? > > > How the udc calls gadget driver the disconnection has happened when > > > the usb cable is disconnected from the host? > > > > > > Usually, we call gadget's disconnect at two situations > > > > > > - udc's reset handler if udc's speed is not UNKNOWN, it is usually happened > > > when the host sends reset after enumeration. > > > - udc's disconnect handler, it is usually happened when the usb cable > > > is disconnected from host. > > > > Hmm, usually the two situations, but according to the commit log, s3c > > hsotg does not support Disconnected interrupt for device mode, > > so the second situation does not happen for s3c hsotg, therefore, he has > > to disconnect the connection before it is connected again. > > Why does he need to do that? Why not just skip the disconnect > notification if the hardware can't detect a disconnect? > > It makes no sense at all to call a disconnect handler from within the > SET_ADDRESS routine. FWIW, here is the section from the DWC2 databook that describes how a disconnect should be handled for the device: When OTG_MODE is set to 0, 1, or 3, the device disconnect flow is as follows: 1. When the USB cable is unplugged or when the VBUS is switched off by the Host, the Device core triggers GINTSTS.OTGInt [bit 2] interrupt bit. 2. When the device application detects GINTSTS.OTGInt interrupt, it checks that the GOTGINT.SesEndDet (Session End Detected) bit is set to 1'b1. When OTG_MODE is set to 2 or 4, the device disconnect flow is as follows: 1. When the USB cable is unplugged or when the VBUS is switched off by the Host, the Device core triggers GINTSTS.USBRst [bit 12] interrupt bit. 2. When the device application detects GINTSTS.USBRst, the application sets a timeout check for SET ADDRESS Control Xfer from Host. 3. If application does not receive SET ADDRESS Control Xfer from Host before the timeout period, it is treated as a device disconnection. OTG_MODE is a configuration parameter that is set when the core is built. From this discussion, it sounds like the s3c-hsotg core is built for either mode 2 or 4. So SET ADDRESS should be involved, but not in the way the driver is currently doing it. Unfortunately I don't have the s3c-hsotg hardware, so I can't work on this myself. -- Paul -- 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
