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authorJason Wessel <jason.wessel@windriver.com>2009-05-11 20:24:07 (GMT)
committerGreg Kroah-Hartman <gregkh@suse.de>2009-06-16 04:44:45 (GMT)
commit715b1dc01fe44537e8fce9566e4bb48d6821d84b (patch)
treeb1fc0b5c61a7317e7104468afddad544fb3fc34c /include
parentb0cda8c5f7b652c6c27bcb3891d174534d2f1a91 (diff)
downloadlinux-fsl-qoriq-715b1dc01fe44537e8fce9566e4bb48d6821d84b.tar.xz
USB: usb_debug, usb_generic_serial: implement multi urb write
The usb_debug driver, when used as the console, will always fail to insert the carriage return and new line sequence as well as randomly drop console output. This is a result of only having the single write_urb and that the tty layer will have a lock that prevents the processing of the back to back urb requests. The solution is to allow more than one urb to be outstanding and have a slightly deeper transmit queue. The idea and some code is borrowed from the ftdi_sio usb driver. The generic usb serial driver was modified so as to allow the classic method of 1 write urb, or a multi write urb scheme with N allowed outstanding urbs where N is controlled by max_in_flight_urbs. When max_in_flight_urbs in a "struct usb_serial_driver" is non zero the multi write urb scheme will be used. The size of 4000 was selected for the usb_debug driver so that the driver lowers possibility of losing the queued console messages during the kernel startup. Signed-off-by: Jason Wessel <jason.wessel@windriver.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'include')
-rw-r--r--include/linux/usb/serial.h4
1 files changed, 4 insertions, 0 deletions
diff --git a/include/linux/usb/serial.h b/include/linux/usb/serial.h
index 8cdfed7..e2938fd 100644
--- a/include/linux/usb/serial.h
+++ b/include/linux/usb/serial.h
@@ -91,6 +91,9 @@ struct usb_serial_port {
int write_urb_busy;
__u8 bulk_out_endpointAddress;
+ int tx_bytes_flight;
+ int urbs_in_flight;
+
wait_queue_head_t write_wait;
struct work_struct work;
char throttled;
@@ -207,6 +210,7 @@ struct usb_serial_driver {
struct device_driver driver;
struct usb_driver *usb_driver;
struct usb_dynids dynids;
+ int max_in_flight_urbs;
int (*probe)(struct usb_serial *serial, const struct usb_device_id *id);
int (*attach)(struct usb_serial *serial);