USB: increase cdc-acm write throughput

the following patch uses 16 write urbs and a writsize of wMaxPacketSize
* 20.  With this patch I get the maximum througput from my linux system
with 20MB/sec read and 15 MB/sec write (full speed 1 MB/sec both)

I also deleted the flag URB_NO_FSBR for the writeurbs, because this
makes my full speed devices significant slower.

Signed-off-by: David Engraf <david.engraf@netcom.eu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 4 insertions, 3 deletions

diff --git a/drivers/usb/class/cdc-acm.h b/drivers/usb/class/cdc-acm.h
index 8df6a57dcf9e..046e064b033a 100644
--- a/drivers/usb/class/cdc-acm.h
+++ b/drivers/usb/class/cdc-acm.h
@@ -59,7 +59,7 @@
  * when processing onlcr, so we only need 2 buffers. These values must be
  * powers of 2.
  */
-#define ACM_NW  2
+#define ACM_NW  16
 #define ACM_NR  16
 
 struct acm_wb {
@@ -67,6 +67,8 @@ struct acm_wb {
         dma_addr_t dmah;
         int len;
         int use;
+        struct urb              *urb;
+        struct acm              *instance;
 };
 
 struct acm_rb {
@@ -88,7 +90,7 @@ struct acm {
         struct usb_interface *control;                  /* control interface */
         struct usb_interface *data;                     /* data interface */
         struct tty_struct *tty;                         /* the corresponding tty */
-        struct urb *ctrlurb, *writeurb;                 /* urbs */
+        struct urb *ctrlurb;                    /* urbs */
         u8 *ctrl_buffer;                                /* buffers of urbs */
         dma_addr_t ctrl_dma;                            /* dma handles of buffers */
         u8 *country_codes;                              /* country codes from device */
@@ -103,7 +105,6 @@ struct acm {
         struct list_head spare_read_urbs;
         struct list_head spare_read_bufs;
         struct list_head filled_read_bufs;
-        int write_current;                              /* current write buffer */
         int write_used;                                 /* number of non-empty write buffers */
         int write_ready;                                /* write urb is not running */
         spinlock_t write_lock;