> > > > > When application does a read or even mount of the flash device how > > > is that information passed on to the device driver so that it can > > > convert that to specific Ctrl/Bulk transfer types and pass it on to > > > HCD? > > > > I believe the driver stack will look something like this: > > > > App that calls read() USERMODE > > ------------------------------------------ > > File system driver (like ext3, fat32) KERNEL MODE > > SCSI driver > >USB-Storage > > usbcore > > USB Host controller driver (like EHCI) > > PCI driver > > ------------------------------------------ > > HARDWARE > > I have a doubt here. I am not much familiar with USB-storage API but, > does this mean USB-Storage driver registers with the SCSI driver and > the information flow happens that way? I am confused because if we see > normal devices like serial port which have a device files like > /dev/ttyS0 they have a specific major, minor number which the driver > specifies while registering the I can see how the system calls get > routed through to the specific driver. But in the case of USB, when > the class specific driver registers with the respective subsystem > (USB-storage with SCSI/file system layer) how does the USB-Storage > driver specify to SCSI driver that it is taking care of the flash > device?
I'm not a SCSI guru, but... Yes, I believe usb-storage registers with the SCSI stack. And I think it happens here: http://www.linux-m32r.org/lxr/http/source/drivers/usb/storage/usb.c?v=2. 6.20-rc1;a=i386#L1007 > > > > > > > > > > Does the same process happen for all of the devices? Like if a USB > > > keyboard is connected and if I want to read from USB keyboard, I will > > > still read from standard keyboard interface? > > > > Yes, but obviously the driver stack looks a little different. > > In the case of HID I think it looks something like this... > > > > App like X USERMODE > > ------------------------------------------ > > HID KERNEL MODE > > usbcore > > USB Host controller driver (like EHCI) > > PCI driver > > ------------------------------------------ > > HARDWARE > > > > > > > Here how will HID layer differentiate between USB and PS2 > mouse/keyboard? Will it read from both the interfaces? Again I missed out a driver (hid-core?). This driver should register with HID and translation the HID messages to send to usbcore... App like X USERMODE ------------------------------------------ HID KERNEL MODE hid-core usbcore USB Host controller driver (like EHCI) PCI driver ------------------------------------------ HARDWARE See: http://www.linux-m32r.org/lxr/http/source/drivers/usb/input/hid-core.c?v =2.6.20-rc1;a=i386 dom ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
