Remove multi-urb writes 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@xxxxxxxxx>
---
drivers/usb/serial/aircable.c | 9 +--
drivers/usb/serial/ftdi_sio.c | 57 ++++++----------
drivers/usb/serial/generic.c | 149 ++++++-----------------------------------
include/linux/usb/serial.h | 7 +--
4 files changed, 48 insertions(+), 174 deletions(-)
diff --git a/drivers/usb/serial/aircable.c b/drivers/usb/serial/aircable.c
index 10ecb54..eadb84a 100644
--- a/drivers/usb/serial/aircable.c
+++ b/drivers/usb/serial/aircable.c
@@ -83,13 +83,12 @@ static const struct usb_device_id id_table[] = {
MODULE_DEVICE_TABLE(usb, id_table);
static int aircable_prepare_write_buffer(struct usb_serial_port *port,
- void **dest, size_t size, const void *src, size_t count)
+ void *dest, size_t size)
{
- unsigned char *buf = *dest;
-
- BUG_ON(port->serial->type->multi_urb_write); /* not implemented */
+ int count;
+ unsigned char *buf = dest;
- count = kfifo_out_locked(&port->write_fifo, *dest + HCI_HEADER_LENGTH,
+ count = kfifo_out_locked(&port->write_fifo, buf + HCI_HEADER_LENGTH,
size - HCI_HEADER_LENGTH, &port->lock);
buf[0] = TX_HEADER_0;
buf[1] = TX_HEADER_1;
diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index f792d57..3df842c 100644
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -779,7 +779,7 @@ static void ftdi_close(struct usb_serial_port *port);
static void ftdi_dtr_rts(struct usb_serial_port *port, int on);
static void ftdi_process_read_urb(struct urb *urb);
static int ftdi_prepare_write_buffer(struct usb_serial_port *port,
- void **dest, size_t size, const void *buf, size_t count);
+ void *dest, size_t size);
static void ftdi_set_termios(struct tty_struct *tty,
struct usb_serial_port *port, struct ktermios *old);
static int ftdi_tiocmget(struct tty_struct *tty, struct file *file);
@@ -805,8 +805,8 @@ static struct usb_serial_driver ftdi_sio_device = {
.usb_driver = &ftdi_driver,
.id_table = id_table_combined,
.num_ports = 1,
+ .bulk_out_size = 256,
.bulk_in_size = 512,
- .multi_urb_write = 1,
.probe = ftdi_sio_probe,
.port_probe = ftdi_sio_port_probe,
.port_remove = ftdi_sio_port_remove,
@@ -1528,15 +1528,6 @@ static int ftdi_sio_port_probe(struct usb_serial_port *port)
quirk->port_probe(priv);
priv->port = port;
-
- /* Free port's existing write urb and transfer buffer. */
- if (port->write_urb) {
- usb_free_urb(port->write_urb);
- port->write_urb = NULL;
- }
- kfree(port->bulk_out_buffer);
- port->bulk_out_buffer = NULL;
-
usb_set_serial_port_data(port, priv);
ftdi_determine_type(port);
@@ -1744,42 +1735,34 @@ static void ftdi_close(struct usb_serial_port *port)
* The new devices do not require this byte
*/
static int ftdi_prepare_write_buffer(struct usb_serial_port *port,
- void **dest, size_t size, const void *src, size_t count)
+ void *dest, size_t size)
{
struct ftdi_private *priv;
- unsigned char *buffer;
- int len;
-
- BUG_ON(!port->serial->type->multi_urb_write); /* not implemented */
+ int count;
+ unsigned long flags;
priv = usb_get_serial_port_data(port);
- len = count;
- if (priv->chip_type == SIO && count != 0)
- len += ((count - 1) / (priv->max_packet_size - 1)) + 1;
-
- buffer = kmalloc(len, GFP_ATOMIC);
- if (!buffer) {
- dev_err(&port->dev, "%s - could not allocate buffer\n",
- __func__);
- return -ENOMEM;
- }
-
if (priv->chip_type == SIO) {
- int i, msg_len;
-
- for (i = 0; i < len; i += priv->max_packet_size) {
- msg_len = min_t(int, len - i, priv->max_packet_size) - 1;
- buffer[i] = (msg_len << 2) + 1;
- memcpy(&buffer[i + 1], src, msg_len);
- src += msg_len;
+ unsigned char *buffer = dest;
+ int i, len, c;
+
+ count = 0;
+ spin_lock_irqsave(&port->lock, flags);
+ for (i = 0; i < size - 1; i += priv->max_packet_size) {
+ len = min_t(int, size - i, priv->max_packet_size) - 1;
+ buffer[i] = (len << 2) + 1;
+ c = kfifo_out(&port->write_fifo, &buffer[i + 1], len);
+ if (!c)
+ break;
+ count += c + 1;
}
+ spin_unlock_irqrestore(&port->lock, flags);
} else {
- memcpy(buffer, src, count);
+ count = kfifo_out_locked(&port->write_fifo, dest, size,
+ &port->lock);
}
- *dest = buffer;
-
return count;
}
diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c
index 93ebaba..053db42 100644
--- a/drivers/usb/serial/generic.c
+++ b/drivers/usb/serial/generic.c
@@ -24,8 +24,6 @@
static int debug;
-#define MAX_TX_URBS 40
-
#ifdef CONFIG_USB_SERIAL_GENERIC
static int generic_probe(struct usb_interface *interface,
@@ -170,92 +168,12 @@ void usb_serial_generic_close(struct usb_serial_port *port)
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;
+ return kfifo_out_locked(&port->write_fifo, dest, size, &port->lock);
}
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;
-}
-
/**
* usb_serial_generic_write_start - kick off an URB write
* @port: Pointer to the &struct usb_serial_port data
@@ -284,8 +202,8 @@ retry:
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);
@@ -326,7 +244,6 @@ retry:
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);
@@ -338,23 +255,18 @@ int usb_serial_generic_write(struct tty_struct *tty,
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;
@@ -364,10 +276,7 @@ int usb_serial_generic_write_room(struct tty_struct *tty)
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);
@@ -377,7 +286,6 @@ int usb_serial_generic_write_room(struct tty_struct *tty)
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;
@@ -387,10 +295,7 @@ int usb_serial_generic_chars_in_buffer(struct tty_struct *tty)
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);
@@ -477,35 +382,25 @@ void usb_serial_generic_write_bulk_callback(struct urb *urb)
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;
- port->tx_urbs--;
- 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) {
+ dbg("%s - non-zero urb status: %d", __func__, status);
spin_lock_irqsave(&port->lock, flags);
- port->tx_bytes -= urb->transfer_buffer_length;
- set_bit(i, &port->write_urbs_free);
+ kfifo_reset_out(&port->write_fifo);
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);
- }
+ } else {
+ 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);
diff --git a/include/linux/usb/serial.h b/include/linux/usb/serial.h
index b88afbc..a7befd0 100644
--- a/include/linux/usb/serial.h
+++ b/include/linux/usb/serial.h
@@ -110,7 +110,6 @@ struct usb_serial_port {
unsigned long flags;
int tx_bytes;
- int tx_urbs;
wait_queue_head_t write_wait;
struct work_struct work;
@@ -235,8 +234,6 @@ 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;
@@ -288,7 +285,7 @@ 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)
@@ -342,7 +339,7 @@ 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);
--
1.7.0.2
--
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