Smallpacket (#26)

* Add support for larger files. Based on original patch by ZoltanSzenczi: https://github.com/raspberrypi/tools/pull/20 * Fix typo in max transfer size. Original patch had a magic number of "LIBUSB_MAX_TRANSFER 507904" Assume that 496K ia a typo for 4096K, although 8M also works for me. * Put back out_ep and long timeout. Master uses out_ep variable instead of hard coding 0x01. Master also sets a much longer time out for the transfer. Transfering 4MB takes almost 5 seconds, so the original patch was dangerously close to timing out here. Master uses 100 second timeout, which is plenty. * Use 16KB instead of 4MB. The usbfs buffer memory is apparently shared across all usbfs devs. So we should try not to use a huge amount of it. Using a 16KB buffer here has no observable impact on performance as the trasnfer will be split up in to packets at least that small anyway. This also removes the abort counter. That doesn't seem to do anything except make the transfer fail if it has to be split into more than 20 parts. There is no "retry" code to break out of; the loop always aborts after a single error. * Reduce the timeout for 16KB blocks. Since the block size is reduced we no longer need to set a huge time out of 100 seconds. 5 seconds should be plenty to transfer 16KB. It should in fact take well under 1 second.

Smallpacket (#26)
* Add support for larger files. Based on original patch by ZoltanSzenczi: https://github.com/raspberrypi/tools/pull/20 * Fix typo in max transfer size. Original patch had a magic number of "LIBUSB_MAX_TRANSFER 507904" Assume that 496K ia a typo for 4096K, although 8M also works for me. * Put back out_ep and long timeout. Master uses out_ep variable instead of hard coding 0x01. Master also sets a much longer time out for the transfer. Transfering 4MB takes almost 5 seconds, so the original patch was dangerously close to timing out here. Master uses 100 second timeout, which is plenty. * Use 16KB instead of 4MB. The usbfs buffer memory is apparently shared across all usbfs devs. So we should try not to use a huge amount of it. Using a 16KB buffer here has no observable impact on performance as the trasnfer will be split up in to packets at least that small anyway. This also removes the abort counter. That doesn't seem to do anything except make the transfer fail if it has to be split into more than 20 parts. There is no "retry" code to break out of; the loop always aborts after a single error. * Reduce the timeout for 16KB blocks. Since the block size is reduced we no longer need to set a huge time out of 100 seconds. 5 seconds should be plenty to transfer 16KB. It should in fact take well under 1 second.
Phil Elwell · Gordon Hollingworth
1 parent 2e03233e
Showing 1 changed file with 13 additions and 4 deletions
main.c
@@ -189,9 +189,12 @@ int Initialize_Device(libusb_context ** ctx, libusb_device_handle ** usb_device)
 	return ret;
 }
  
+#define LIBUSB_MAX_TRANSFER (16 * 1024)
+
 int ep_write(void *buf, int len, libusb_device_handle * usb_device)
 {
 	int a_len = 0;
+	int sending, sent;
 	int ret =
 	    libusb_control_transfer(usb_device, LIBUSB_REQUEST_TYPE_VENDOR, 0,
 				    len & 0xffff, len >> 16, NULL, 0, 1000);
@@ -202,12 +205,18 @@ int ep_write(void *buf, int len, libusb_device_handle * usb_device)
 		return ret;
 	}
  
-	if(len > 0)
+	while(len > 0)
 	{
-		ret = libusb_bulk_transfer(usb_device, out_ep, buf, len, &a_len, 100000);
-		if(verbose)
-			printf("libusb_bulk_transfer returned %d\n", ret);
+		sending = len < LIBUSB_MAX_TRANSFER ? len : LIBUSB_MAX_TRANSFER;
+		ret = libusb_bulk_transfer(usb_device, out_ep, buf, sending, &sent, 5000);
+		if (ret)
+			break;
+		a_len += sent;
+		buf += sent;
+		len -= sent;
 	}
+	if(verbose)
+		printf("libusb_bulk_transfer sent %d bytes; returned %d\n", a_len, ret);
  
 	return a_len;
 }