1 files changed, 27 insertions, 14 deletions

diff --git a/usbmuxd/usb-linux.c b/usbmuxd/usb-linux.c
index 9634d14..fb22d03 100644
--- a/usbmuxd/usb-linux.c
+++ b/usbmuxd/usb-linux.c
@@ -45,6 +45,7 @@ struct usb_device {
         int alive;
         struct libusb_transfer *rx_xfer;
         struct collection tx_xfers;
+        int wMaxPacketSize;
 };
 
 static struct collection device_list;
@@ -133,26 +134,15 @@ int usb_send(struct usb_device *dev, const unsigned char *buf, int length)
         struct libusb_transfer *xfer = libusb_alloc_transfer(0);
         libusb_fill_bulk_transfer(xfer, dev->dev, BULK_OUT, (void*)buf, length, tx_callback, dev, 0);
         xfer->flags = LIBUSB_TRANSFER_SHORT_NOT_OK;
+        if (length % dev->wMaxPacketSize == 0) {
+                xfer->flags |= LIBUSB_TRANSFER_ZERO_PACKET;
+        }
         if((res = libusb_submit_transfer(xfer)) < 0) {
                 usbmuxd_log(LL_ERROR, "Failed to submit TX transfer %p len %d to device %d-%d: %d", buf, length, dev->bus, dev->address, res);
                 libusb_free_transfer(xfer);
                 return res;
         }
         collection_add(&dev->tx_xfers, xfer);
-        if((length % 512) == 0) {
-                usbmuxd_log(LL_DEBUG, "Send ZLP");
-                // Send Zero Length Packet
-                xfer = libusb_alloc_transfer(0);
-                void *buffer = malloc(1);
-                libusb_fill_bulk_transfer(xfer, dev->dev, BULK_OUT, buffer, 0, tx_callback, dev, 0);
-                xfer->flags = LIBUSB_TRANSFER_SHORT_NOT_OK;
-                if((res = libusb_submit_transfer(xfer)) < 0) {
-                        usbmuxd_log(LL_ERROR, "Failed to submit TX ZLP transfer to device %d-%d: %d", dev->bus, dev->address, res);
-                        libusb_free_transfer(xfer);
-                        return res;
-                }
-                collection_add(&dev->tx_xfers, xfer);
-        }
         return 0;
 }
 
@@ -314,6 +304,29 @@ static int usb_discover(void)
                 usbdev->pid = devdesc.idProduct;
                 usbdev->dev = handle;
                 usbdev->alive = 1;
+                usbdev->wMaxPacketSize = 0;
+                struct libusb_config_descriptor *cfg;
+                if (libusb_get_active_config_descriptor(dev, &cfg) == 0
+                                && cfg && cfg->bNumInterfaces >= (USB_INTERFACE+1)) {
+                        const struct libusb_interface *ifp = &cfg->interface[USB_INTERFACE];
+                        if (ifp && ifp->num_altsetting >= 1) {
+                                const struct libusb_interface_descriptor *as = &ifp->altsetting[0];
+                                int i;
+                                for (i = 0; i < as->bNumEndpoints; i++) {
+                                        const struct libusb_endpoint_descriptor *ep = &as->endpoint[i];
+                                        if (ep->bEndpointAddress == BULK_OUT) {
+                                                usbdev->wMaxPacketSize = ep->wMaxPacketSize;
+                                        }
+                                }
+                        }
+                }
+                if (usbdev->wMaxPacketSize == 0) {
+                        usbmuxd_log(LL_ERROR, "Could not determine wMaxPacketSize for device %d-%d, setting to 64", usbdev->bus, usbdev->address);
+                        usbdev->wMaxPacketSize = 64;
+                } else {
+                        usbmuxd_log(LL_INFO, "Using wMaxPacketSize=%d for device %d-%d", usbdev->wMaxPacketSize, usbdev->bus, usbdev->address);
+                }
+
                 collection_init(&usbdev->tx_xfers);
 
                 collection_add(&device_list, usbdev);