Remove urb request size maximum.
The 16kB maximum for transfers was removed from
the kernel in 3.3. Devio has since supported
arbitrary transfer sizes through scatter gather.
See the following kernel patches for context:
"USB: change the memory limits in usbfs URB submission"
"usbdevfs: Use scatter-gather lists for large bulk transfers"
Bug: 67683483
Test: Run usb_async_test app with USB3 : 38MB/s -> 300MB/s
Change-Id: Ia52440cb725561b0f1db1a75aa1b8ab952585826
diff --git a/libusbhost/usbhost.c b/libusbhost/usbhost.c
index fa0191b..cb8d430 100644
--- a/libusbhost/usbhost.c
+++ b/libusbhost/usbhost.c
@@ -64,10 +64,6 @@
// Some devices fail to send string descriptors if we attempt reading > 255 bytes
#define MAX_STRING_DESCRIPTOR_LENGTH 255
-// From drivers/usb/core/devio.c
-// I don't know why this isn't in a kernel header
-#define MAX_USBFS_BUFFER_SIZE 16384
-
#define MAX_USBFS_WD_COUNT 10
struct usb_host_context {
@@ -664,10 +660,6 @@
{
struct usbdevfs_bulktransfer ctrl;
- // need to limit request size to avoid EINVAL
- if (length > MAX_USBFS_BUFFER_SIZE)
- length = MAX_USBFS_BUFFER_SIZE;
-
memset(&ctrl, 0, sizeof(ctrl));
ctrl.ep = endpoint;
ctrl.len = length;
@@ -727,11 +719,7 @@
urb->status = -1;
urb->buffer = req->buffer;
- // need to limit request size to avoid EINVAL
- if (req->buffer_length > MAX_USBFS_BUFFER_SIZE)
- urb->buffer_length = MAX_USBFS_BUFFER_SIZE;
- else
- urb->buffer_length = req->buffer_length;
+ urb->buffer_length = req->buffer_length;
do {
res = ioctl(req->dev->fd, USBDEVFS_SUBMITURB, urb);