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authorJoris van Rantwijk <jorispubl@xs4all.nl>2007-02-01 20:08:18 +0100
committerGreg Kroah-Hartman <gregkh@suse.de>2007-02-16 15:32:18 -0800
commit253ca923281aec6975ec4028ddbc58e865d8d13d (patch)
tree837b437f40ecb75174917e0623b6f4e2cdcc6f46 /include/linux/usb
parentb544d7499cc47fc26e9dbacd7b9cabc67d2bdf2e (diff)
USB: add flow control to usb-serial generic driver.
I added two fields to struct usb_serial_port to keep track of the throttle state. Other usb-serial drivers typically use private data for such things, but the generic driver can not really do that because some of its code is also used by other drivers (which may have their own private data needs). As it is, I am not sure that this patch is useful in all scenarios. It is certainly helpful for low-bandwidth devices that can hold their data in response to throttling. But for devices that pump data in real-time as fast as possible (webcam, A/D converter, etc), throttling may actually cause more data loss. From: Joris van Rantwijk <jorispubl@xs4all.nl> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'include/linux/usb')
-rw-r--r--include/linux/usb/serial.h6
1 files changed, 6 insertions, 0 deletions
diff --git a/include/linux/usb/serial.h b/include/linux/usb/serial.h
index 33dcd857669..32acbae28d2 100644
--- a/include/linux/usb/serial.h
+++ b/include/linux/usb/serial.h
@@ -54,6 +54,8 @@
* @write_wait: a wait_queue_head_t used by the port.
* @work: work queue entry for the line discipline waking up.
* @open_count: number of times this port has been opened.
+ * @throttled: nonzero if the read urb is inactive to throttle the device
+ * @throttle_req: nonzero if the tty wants to throttle us
*
* This structure is used by the usb-serial core and drivers for the specific
* ports of a device.
@@ -88,6 +90,8 @@ struct usb_serial_port {
wait_queue_head_t write_wait;
struct work_struct work;
int open_count;
+ char throttled;
+ char throttle_req;
struct device dev;
};
#define to_usb_serial_port(d) container_of(d, struct usb_serial_port, dev)
@@ -269,6 +273,8 @@ extern int usb_serial_generic_write_room (struct usb_serial_port *port);
extern int usb_serial_generic_chars_in_buffer (struct usb_serial_port *port);
extern void usb_serial_generic_read_bulk_callback (struct urb *urb);
extern void usb_serial_generic_write_bulk_callback (struct urb *urb);
+extern void usb_serial_generic_throttle (struct usb_serial_port *port);
+extern void usb_serial_generic_unthrottle (struct usb_serial_port *port);
extern void usb_serial_generic_shutdown (struct usb_serial *serial);
extern int usb_serial_generic_register (int debug);
extern void usb_serial_generic_deregister (void);