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--- linux/drivers/usb/acm.c~45-acm-tty.patch 2006-06-07 11:21:21.648422000 +0200
+++ linux/drivers/usb/acm.c 2006-06-09 17:20:51.735793750 +0200
@@ -139,6 +139,8 @@
* Internal driver structures.
*/
+#define TD_SIZE 16384
+
struct acm {
struct usb_device *dev; /* the coresponding usb device */
struct usb_interface *iface; /* the interfaces - +0 control +1 data */
@@ -153,6 +155,11 @@
unsigned int minor; /* acm minor number */
unsigned char throttle; /* throttled by tty layer */
unsigned char clocal; /* termios CLOCAL */
+ unsigned long throttle_start;
+ unsigned char resubmit_to_unthrottle; /* Leftover data from last operation */
+ unsigned char *throttle_data;
+ int td_len;
+ int td_busy;
};
/* global params controlling max sizes for read, write, control */
@@ -166,6 +173,96 @@
#define ACM_READY(acm) (acm && acm->dev && acm->used)
+
+/*
+ * Helper functions to optimize throttleing
+ */
+static int
+acm_fill_tty(struct urb *urb, struct tty_struct *tty, unsigned char *data, int length)
+{
+ struct acm *acm = urb->context;
+ int n = 0;
+ /*printk("acm_fill_tty: %d bytes\n", length);*/
+ if (!urb->status && !acm->throttle) {
+ for (n = 0; n < length && !acm->throttle; n++) {
+ /* if we insert more than TTY_FLIPBUF_SIZE characters,
+ * we drop them. */
+ if (tty->flip.count >= TTY_FLIPBUF_SIZE) {
+ tty_flip_buffer_push(tty);
+ }
+ tty_insert_flip_char(tty, data[n], 0);
+ }
+ tty_flip_buffer_push(tty);
+ }
+ /*printk("copied %d bytes.\n", n);*/
+ return n;
+}
+
+static int
+acm_shift_if_throttle(unsigned char *data, int *length, int shift_by)
+{
+ if (shift_by < *length) {
+ dbg("need to shift uncopied %d bytes to front.", *length - shift_by);
+ memmove(data, data + shift_by, *length - shift_by);
+ *length -= shift_by;
+ return 1;
+ }
+ return 0;
+}
+
+static int
+acm_buffer_if_thottle(struct acm *acm, unsigned char *data, int start, int *length)
+{
+ int copied = *length;
+ if (start < *length) {
+ int space = TD_SIZE - acm->td_len;
+ int needed = *length - start;
+ copied = (space < needed)? space: needed;
+ dbg("need to push %d to throttle buffer, can copy %d.",
+ needed, copied);
+ memcpy(acm->throttle_data + acm->td_len, data, copied);
+ acm->td_len += copied;
+ *length -= copied;
+ }
+ return copied;
+}
+
+static int
+acm_empty_throttle(struct urb *urb, struct tty_struct *tty)
+{
+ unsigned long flags;
+ struct acm *acm = urb->context;
+
+ save_flags(flags);
+ cli();
+
+ if (acm->td_busy) {
+ restore_flags(flags);
+ return 0;
+ }
+ acm->td_busy = 1;
+ restore_flags(flags);
+
+ if (acm->td_len > 0) {
+
+ dbg("acm_empty_throttle: trying to empty throttle buffer: %d bytes.",
+ acm->td_len);
+
+ /* if there has been something left from previous operations
+ * we try to complete this before looking at the urb */
+ int copied = acm_fill_tty(urb, tty, acm->throttle_data, acm->td_len);
+ if (acm_shift_if_throttle(acm->throttle_data, &acm->td_len, copied)) {
+ /* we were unable to empty the throttle data, so we can't
+ * copy anything more now */
+ acm->td_busy = 0;
+ return 0;
+ }
+ acm->td_len = 0;
+ }
+ acm->td_busy = 0;
+ return 1;
+}
+
/*
* Functions for ACM control messages.
*/
@@ -238,36 +335,40 @@
struct acm *acm = urb->context;
struct tty_struct *tty = acm->tty;
unsigned char *data = urb->transfer_buffer;
- int i = 0;
+ int copied = 0;
+ int buffered = 0;
if (!ACM_READY(acm)) return;
- if (urb->status)
+ if (urb->status) {
dbg("nonzero read bulk status received: %d", urb->status);
+ }
- if (!urb->status && !acm->throttle) {
- for (i = 0; i < urb->actual_length && !acm->throttle; i++) {
- /* if we insert more than TTY_FLIPBUF_SIZE characters,
- * we drop them. */
- if (tty->flip.count >= TTY_FLIPBUF_SIZE) {
- tty_flip_buffer_push(tty);
- }
- tty_insert_flip_char(tty, data[i], 0);
- }
- tty_flip_buffer_push(tty);
+ dbg("acm_read_bulk, calling acm_empty_throttle()");
+ if (!acm_empty_throttle(urb, tty)) {
+ dbg("could not empty throttle buffer, entering throttle state, acm->td_busy: %d.", acm->td_busy);
}
+ /* got here, either there was nothing in the throttle data or it could
+ * all be copied without throttleing again */
+ copied = acm_fill_tty(urb, tty, data, urb->actual_length);
if (acm->throttle) {
- memmove(data, data + i, urb->actual_length - i);
- urb->actual_length -= i;
- return;
+ int length = urb->actual_length;
+ buffered = acm_buffer_if_thottle(acm, data, copied, &urb->actual_length);
+ if (buffered < length - copied
+ && acm_shift_if_throttle(data, &urb->actual_length, copied + buffered)) {
+ printk("need to resubmit to unthrottle\n");
+ acm->resubmit_to_unthrottle = 1;
+ return;
+ }
}
urb->actual_length = 0;
urb->dev = acm->dev;
- if (usb_submit_urb(urb))
+ if (usb_submit_urb(urb)) {
dbg("failed resubmitting read urb");
+ }
}
static void acm_write_bulk(struct urb *urb)
@@ -330,7 +431,12 @@
acm_set_control(acm, acm->ctrlout = ACM_CTRL_DTR | ACM_CTRL_RTS);
- /* force low_latency on so that our tty_push actually forces the data through,
+ acm->resubmit_to_unthrottle = 0;
+ acm->td_len = 0;
+ acm->td_busy = 0;
+ acm->throttle_data = kmalloc(TD_SIZE * sizeof (*acm->throttle_data), GFP_KERNEL);
+
+ /* force low_latency on so that our tty_push actually forces the data through,
otherwise it is scheduled, and with high data rates data can get lost. */
tty->low_latency = 1;
@@ -352,6 +458,7 @@
} else {
tty_unregister_devfs(&acm_tty_driver, acm->minor);
acm_table[acm->minor] = NULL;
+ kfree(acm->throttle_data);
kfree(acm);
}
}
@@ -363,8 +470,16 @@
struct acm *acm = tty->driver_data;
if (!ACM_READY(acm)) return -EINVAL;
- if (acm->writeurb.status == -EINPROGRESS) return 0;
- if (!count) return 0;
+
+ if (acm->writeurb.status == -EINPROGRESS) {
+ dbg("tty_write in progress");
+ return 0;
+ }
+
+ if (!count) {
+ dbg("tty_write: nothing to write");
+ return 0;
+ }
count = (count > acm->writesize) ? acm->writesize : count;
@@ -401,16 +516,32 @@
{
struct acm *acm = tty->driver_data;
if (!ACM_READY(acm)) return;
+ dbg("acm_tty_throttle ON %ld ---> %ld", jiffies-acm->throttle_start, jiffies);
acm->throttle = 1;
+ acm->throttle_start = jiffies;
}
static void acm_tty_unthrottle(struct tty_struct *tty)
{
struct acm *acm = tty->driver_data;
if (!ACM_READY(acm)) return;
+ dbg("acm_tty_throttle OFF %ld ---> %ld", jiffies, jiffies-acm->throttle_start);
acm->throttle = 0;
- if (acm->readurb.status != -EINPROGRESS)
+
+ dbg("acm_tty_unthrottle, calling acm_empty_throttle()");
+ if (!acm_empty_throttle(&acm->readurb, tty)) {
+ if (acm->td_busy) {
+ printk("***** pending acm_empty_throttle!\n");
+ } else {
+ dbg("throttle not emptied.\n");
+ }
+ }
+
+ if (acm->resubmit_to_unthrottle != 0) {
+ dbg("resubmit_to_unthrottle: acm_read_bulk");
+ acm->resubmit_to_unthrottle = 0;
acm_read_bulk(&acm->readurb);
+ }
}
static void acm_tty_break_ctl(struct tty_struct *tty, int state)
|
