On Sun, 22 Jul 2012, chetan cr123 wrote: > On Sat, Jul 21, 2012 at 11:35 PM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > > On Sat, 21 Jul 2012, chetan cr123 wrote: > > > >> Hello, > >> Kindly let me know > >> how an usb device connection is reported to kernel when we plug an usb cable. > >> I see that Udev/ueventd is responsible for that. > > > > It sounds like you're talking about the device's kernel, not the host's > > kernel. > > > I am talking bout usb device kernel (not the host). > but for me tablet/mobile should work as both as > 1. As device when we connect to PC. > 2. As host when we connect a pendriver or some other device when > connected to my tablet. > > so i was asking about udev/uevent and how the usb plug in > reported/detected to kerenl. so that in run time i can decide and load > / unload the USB gadget and USB host driver. The host side is easy enough. When a new USB device is detected a uevent message is sent to udev. Then udev rules cause the appropriate driver to be loaded. Nothing like that happens on the device side, though. > >> I want to know how exactly usb device will report to (kernel or udev) > >> when an device is plugged. > > > > Answer: Currently connections are not reported. > > Ok fine. then kindly let me know how kernel or OS comes to know USB is connected? > > There was some discussion about having the gadget core export a > > pollable sysfs file that would indicate the current USB connection > > state. But nobody has written any code. > > > >> how can to create an sysfs(node) from gadget driver and this driver > >> reports to Udev/uevent when an USB device is connected. > >> So that Application can read Uevents of USB plugin and do the > >> necessary action (in my case disable the block driver and load usb > >> gadget mass storage to communicate with PC -----> SD-card of > >> Tablet/mobile) . > >> Kindly let me know how can i do this. > > > > There is no way to do this now. > > oh is it. then u mean i cant go with this use case? > I am using Android ICS 4.03 source code for our tablet device. > I saw in some Samsung phone running on Android 2.3. they have > implemented a use case like this. > when we use some files(say mp3 ) playing from SD-card------> block > driver will come into picture. > at the same time when user plugs an USB cable the playing video > stops(to say block driver might be unloaded ) to UI they informs user > about USB connection and loads gadget driver so that we can read write > to SD-card in Tablet(mobile) from computer. > > This i need to implement on my tablet phone. Kindly let me know how > can i do this. If you want to know how to do this under Android then you should ask on an Android-oriented mailing list. The linux-usb mailing list covers only standard Linux, not variants such as Android. Alan Stern -- 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
