C Linux USB Driver | Best way to print URB buffer contents -


i'm new linux usb driver development, , absolutely love far! i'm creating driver xbox 1 controller, , have question guys. in below code, see fill interrupt in urb in open function, , print contents of urb buffer in xb1_int_in_callback() function. best way this? @ moment, i'm using printk(kern_info "int_in_buffer: %s", dev->int_in_buffer), don't see entire urb buffer contents printed, , weird string printed dmesg.

sorry if simple question, i'm new programming , c, i'm still learning go, absolutely love far!

code:

static void xb1_int_in_callback(struct urb *int_in_urb) {     struct xb1_controller *dev = int_in_urb->context;      printk(kern_info "xb1_int_in_callback called");     printk(kern_info "int_in_buffer: %s", dev->int_in_buffer); }  static int xb1_open(struct inode *inode, struct file *file) {     printk(kern_info "open function called..");      struct xb1_controller *dev;     struct usb_interface *interface;     int subminor;     int retval = 0;      subminor = iminor(inode);      interface = usb_find_interface(&xb1_driver, subminor);     if(!interface) {         printk(kern_info "unable locate interface in open            function");         retval = -enodev;         goto exit;     }      dev = usb_get_intfdata(interface);         if(!dev) {             printk(kern_info "unable locate dev structure in open                function");             retval = -enodev;             goto exit;         }      usb_fill_int_urb(dev->int_in_urb, dev->udev, usb_rcvintpipe(dev-                   >udev, dev->int_in_endpoint->bendpointaddress),                  dev->int_in_buffer, dev->int_in_endpoint-                   >wmaxpacketsize, xb1_int_in_callback,                  dev, dev->int_in_endpoint->binterval);      dev->int_in_running = 1;      retval = usb_submit_urb(dev->int_in_urb, gfp_kernel);     if(retval) {         printk(kern_info "unable submit int_in_urb in open          function");         dev->int_in_running = 0;         goto exit;     }      file->private_data = dev;  exit:     return retval; }   static int xb1_probe(struct usb_interface *interface, const struct      usb_device_id *id) {     struct usb_device *udev = interface_to_usbdev(interface);     struct xb1_controller *dev = null;     struct usb_host_interface *iface_desc;     struct usb_endpoint_descriptor *endpoint;     int i;     int retval = -enodev;      if(!udev) {         printk(kern_info "udev null in probe function");         xb1_abort(dev);         return retval;     }      dev = kzalloc(sizeof(struct xb1_controller), gfp_kernel);     if(!dev) {         printk(kern_info "unable allocate memory dev in probe            function");         xb1_abort(dev);         return retval;     }      dev->udev = udev;     dev->interface = interface;      iface_desc = interface->cur_altsetting;      for(i=0; i<iface_desc->desc.bnumendpoints; i++) {         endpoint = &iface_desc->endpoint[i].desc;          if(((endpoint->bendpointaddress & usb_endpoint_dir_mask) ==            usb_dir_in)            && ((endpoint->bmattributes & usb_endpoint_xfertype_mask) ==                usb_endpoint_xfer_int)) {              dev->int_in_endpoint = endpoint;         }     }      if(!dev->int_in_endpoint) {         printk(kern_info "unable locate interrupt in endpoint          interface in probe function");         xb1_abort(dev);         return retval;     }     else {         printk(kern_info "interrupt in endpoint found!");     }

for printing small buffers (up 64 bytes long) use printk format:

raw buffer hex string:

%*ph    00 01 02  ...  3f %*phc   00:01:02: ... :3f %*phd   00-01-02- ... -3f %*phn   000102 ... 3f

for larger buffers use print_hex_dump(). reference here.


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