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Commit 3be61d38 authored by Jerry Zhang's avatar Jerry Zhang
Browse files

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
parent 98aad49d

libusbhost/usbhost.c

+1 −13
Original line number Diff line number Diff line
@@ -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 @@ int usb_device_bulk_transfer(struct usb_device *device, 
{

    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;
@@ -727,10 +719,6 @@ int usb_request_queue(struct usb_request *req) 


    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;



    do {