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| author | Jason Wessel <jason.wessel@windriver.com> | 2009-05-11 15:24:07 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2009-06-15 21:44:45 -0700 |
| commit | 715b1dc01fe44537e8fce9566e4bb48d6821d84b (patch) | |
| tree | b1fc0b5c61a7317e7104468afddad544fb3fc34c /include | |
| parent | b0cda8c5f7b652c6c27bcb3891d174534d2f1a91 (diff) | |
| download | linux-715b1dc01fe44537e8fce9566e4bb48d6821d84b.tar.bz2 | |
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.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/include/linux/usb/serial.h b/include/linux/usb/serial.h index 8cdfed738fe4..e2938fd179e2 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); |