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USB: serial: remove multi-urb write from generic driver

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Remove multi-urb write from the generic driver and simplify the
prepare_write_buffer prototype:

	int (*prepare_write_buffer)(struct usb_serial_port *port,
						void *dest, size_t size);

The default implementation simply fills dest with data from port write
fifo but drivers can override it if they need to process the outgoing
data (e.g. add headers).

Turn ftdi_sio into a generic fifo-based driver, which lowers CPU usage
significantly for small writes while retaining maximum throughput.

Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Johan Hovold 2010-05-05 23:58:13 +02:00 • committed by Greg Kroah-Hartman
parent 27c7acf220
commit c23e5fc1f7
4 changed files with 47 additions and 175 deletions
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8
include/linux/usb/serial.h
View file

@ -67,7 +67,6 @@ enum port_dev_state {
* @write_urbs: pointers to the bulk out urbs for this port
* @write_urbs_free: status bitmap the for bulk out urbs
* @tx_bytes: number of bytes currently in host stack queues
* @tx_urbs: number of urbs currently in host stack queues
* @bulk_out_endpointAddress: endpoint address for the bulk out pipe for this
* port.
* @flags: usb serial port flags
@ -112,7 +111,6 @@ struct usb_serial_port {
__u8 bulk_out_endpointAddress;
int tx_bytes;
int tx_urbs;
unsigned long flags;
wait_queue_head_t write_wait;
@ -238,8 +236,6 @@ struct usb_serial_driver {
struct usb_driver *usb_driver;
struct usb_dynids dynids;
unsigned char multi_urb_write:1;
size_t bulk_in_size;
size_t bulk_out_size;
@ -291,7 +287,7 @@ struct usb_serial_driver {
void (*process_read_urb)(struct urb *urb);
/* Called by the generic write implementation */
int (*prepare_write_buffer)(struct usb_serial_port *port,
void **dest, size_t size, const void *src, size_t count);
void *dest, size_t size);
};
#define to_usb_serial_driver(d) \
container_of(d, struct usb_serial_driver, driver)
@ -345,7 +341,7 @@ extern int usb_serial_generic_submit_read_urb(struct usb_serial_port *port,
gfp_t mem_flags);
extern void usb_serial_generic_process_read_urb(struct urb *urb);
extern int usb_serial_generic_prepare_write_buffer(struct usb_serial_port *port,
void **dest, size_t size, const void *src, size_t count);
void *dest, size_t size);
extern int usb_serial_handle_sysrq_char(struct tty_struct *tty,
struct usb_serial_port *port,
unsigned int ch);