USB: serial: remove multi-urb write from generic driver
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>
diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c
index 3ae1784..fcd30b8 100644
--- a/drivers/usb/serial/generic.c
+++ b/drivers/usb/serial/generic.c
@@ -26,8 +26,6 @@
static int debug;
-#define MAX_TX_URBS 40
-
#ifdef CONFIG_USB_SERIAL_GENERIC
static int generic_probe(struct usb_interface *interface,
@@ -172,90 +170,9 @@
EXPORT_SYMBOL_GPL(usb_serial_generic_close);
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)
{
- if (!*dest) {
- size = count;
- *dest = kmalloc(count, GFP_ATOMIC);
- if (!*dest) {
- dev_err(&port->dev, "%s - could not allocate buffer\n",
- __func__);
- return -ENOMEM;
- }
- }
- if (src) {
- count = size;
- memcpy(*dest, src, size);
- } else {
- count = kfifo_out_locked(&port->write_fifo, *dest, size,
- &port->lock);
- }
- return count;
-}
-EXPORT_SYMBOL_GPL(usb_serial_generic_prepare_write_buffer);
-
-static int usb_serial_multi_urb_write(struct tty_struct *tty,
- struct usb_serial_port *port, const unsigned char *buf, int count)
-{
- unsigned long flags;
- struct urb *urb;
- void *buffer;
- int status;
-
- spin_lock_irqsave(&port->lock, flags);
- if (port->tx_urbs == MAX_TX_URBS) {
- spin_unlock_irqrestore(&port->lock, flags);
- dbg("%s - write limit hit", __func__);
- return 0;
- }
- port->tx_urbs++;
- spin_unlock_irqrestore(&port->lock, flags);
-
- urb = usb_alloc_urb(0, GFP_ATOMIC);
- if (!urb) {
- dev_err(&port->dev, "%s - no free urbs available\n", __func__);
- status = -ENOMEM;
- goto err_urb;
- }
-
- buffer = NULL;
- count = min_t(int, count, PAGE_SIZE);
- count = port->serial->type->prepare_write_buffer(port, &buffer, 0,
- buf, count);
- if (count < 0) {
- status = count;
- goto err_buf;
- }
- usb_serial_debug_data(debug, &port->dev, __func__, count, buffer);
- usb_fill_bulk_urb(urb, port->serial->dev,
- usb_sndbulkpipe(port->serial->dev,
- port->bulk_out_endpointAddress),
- buffer, count,
- port->serial->type->write_bulk_callback, port);
-
- status = usb_submit_urb(urb, GFP_ATOMIC);
- if (status) {
- dev_err(&port->dev, "%s - error submitting urb: %d\n",
- __func__, status);
- goto err;
- }
- spin_lock_irqsave(&port->lock, flags);
- port->tx_bytes += urb->transfer_buffer_length;
- spin_unlock_irqrestore(&port->lock, flags);
-
- usb_free_urb(urb);
-
- return count;
-err:
- kfree(buffer);
-err_buf:
- usb_free_urb(urb);
-err_urb:
- spin_lock_irqsave(&port->lock, flags);
- port->tx_urbs--;
- spin_unlock_irqrestore(&port->lock, flags);
-
- return status;
+ return kfifo_out_locked(&port->write_fifo, dest, size, &port->lock);
}
/**
@@ -286,8 +203,8 @@
urb = port->write_urbs[i];
count = port->serial->type->prepare_write_buffer(port,
- &urb->transfer_buffer,
- port->bulk_out_size, NULL, 0);
+ urb->transfer_buffer,
+ port->bulk_out_size);
urb->transfer_buffer_length = count;
usb_serial_debug_data(debug, &port->dev, __func__, count,
urb->transfer_buffer);
@@ -328,7 +245,6 @@
int usb_serial_generic_write(struct tty_struct *tty,
struct usb_serial_port *port, const unsigned char *buf, int count)
{
- struct usb_serial *serial = port->serial;
int result;
dbg("%s - port %d", __func__, port->number);
@@ -340,23 +256,18 @@
if (!count)
return 0;
- if (serial->type->multi_urb_write)
- return usb_serial_multi_urb_write(tty, port, buf, count);
-
count = kfifo_in_locked(&port->write_fifo, buf, count, &port->lock);
result = usb_serial_generic_write_start(port);
+ if (result)
+ return result;
- if (result >= 0)
- result = count;
-
- return result;
+ return count;
}
EXPORT_SYMBOL_GPL(usb_serial_generic_write);
int usb_serial_generic_write_room(struct tty_struct *tty)
{
struct usb_serial_port *port = tty->driver_data;
- struct usb_serial *serial = port->serial;
unsigned long flags;
int room;
@@ -366,10 +277,7 @@
return 0;
spin_lock_irqsave(&port->lock, flags);
- if (serial->type->multi_urb_write)
- room = (MAX_TX_URBS - port->tx_urbs) * PAGE_SIZE;
- else
- room = kfifo_avail(&port->write_fifo);
+ room = kfifo_avail(&port->write_fifo);
spin_unlock_irqrestore(&port->lock, flags);
dbg("%s - returns %d", __func__, room);
@@ -379,7 +287,6 @@
int usb_serial_generic_chars_in_buffer(struct tty_struct *tty)
{
struct usb_serial_port *port = tty->driver_data;
- struct usb_serial *serial = port->serial;
unsigned long flags;
int chars;
@@ -389,10 +296,7 @@
return 0;
spin_lock_irqsave(&port->lock, flags);
- if (serial->type->multi_urb_write)
- chars = port->tx_bytes;
- else
- chars = kfifo_len(&port->write_fifo) + port->tx_bytes;
+ chars = kfifo_len(&port->write_fifo) + port->tx_bytes;
spin_unlock_irqrestore(&port->lock, flags);
dbg("%s - returns %d", __func__, chars);
@@ -479,35 +383,25 @@
dbg("%s - port %d", __func__, port->number);
- if (port->serial->type->multi_urb_write) {
- kfree(urb->transfer_buffer);
+ for (i = 0; i < ARRAY_SIZE(port->write_urbs); ++i)
+ if (port->write_urbs[i] == urb)
+ break;
+
+ spin_lock_irqsave(&port->lock, flags);
+ port->tx_bytes -= urb->transfer_buffer_length;
+ set_bit(i, &port->write_urbs_free);
+ spin_unlock_irqrestore(&port->lock, flags);
+
+ if (status) {
+ dbg("%s - non-zero urb status: %d", __func__, status);
spin_lock_irqsave(&port->lock, flags);
- port->tx_bytes -= urb->transfer_buffer_length;
- port->tx_urbs--;
+ kfifo_reset_out(&port->write_fifo);
spin_unlock_irqrestore(&port->lock, flags);
} else {
- for (i = 0; i < ARRAY_SIZE(port->write_urbs); ++i)
- if (port->write_urbs[i] == urb)
- break;
-
- spin_lock_irqsave(&port->lock, flags);
- port->tx_bytes -= urb->transfer_buffer_length;
- set_bit(i, &port->write_urbs_free);
- spin_unlock_irqrestore(&port->lock, flags);
-
- if (status) {
- spin_lock_irqsave(&port->lock, flags);
- kfifo_reset_out(&port->write_fifo);
- spin_unlock_irqrestore(&port->lock, flags);
- } else {
- usb_serial_generic_write_start(port);
- }
+ usb_serial_generic_write_start(port);
}
- if (status)
- dbg("%s - non-zero urb status: %d", __func__, status);
-
usb_serial_port_softint(port);
}
EXPORT_SYMBOL_GPL(usb_serial_generic_write_bulk_callback);