1 files changed, 34 insertions, 15 deletions

diff --git a/drivers/char/hvc_console.c b/drivers/char/hvc_console.c
index a0a88aa23f5b..0f9ed7b46a6d 100644
--- a/drivers/char/hvc_console.c
+++ b/drivers/char/hvc_console.c
@@ -47,8 +47,6 @@
 #define HVC_MAJOR       229
 #define HVC_MINOR       0
 
-#define TIMEOUT         (10)
-
 /*
  * Wait this long per iteration while trying to push buffered data to the
  * hypervisor before allowing the tty to complete a close operation.
@@ -104,12 +102,12 @@ static DEFINE_SPINLOCK(hvc_structs_lock);
 /*
  * This value is used to assign a tty->index value to a hvc_struct based
  * upon order of exposure via hvc_probe(), when we can not match it to
- * a console canidate registered with hvc_instantiate().
+ * a console candidate registered with hvc_instantiate().
  */
 static int last_hvc = -1;
 
 /*
- * Do not call this function with either the hvc_strucst_lock or the hvc_struct
+ * Do not call this function with either the hvc_structs_lock or the hvc_struct
  * lock held.  If successful, this function increments the kobject reference
  * count against the target hvc_struct so it should be released when finished.
  */
@@ -162,7 +160,7 @@ void hvc_console_print(struct console *co, const char *b, unsigned count)
         if (index >= MAX_NR_HVC_CONSOLES)
                 return;
 
-        /* This console adapter was removed so it is not useable. */
+        /* This console adapter was removed so it is not usable. */
         if (vtermnos[index] < 0)
                 return;
 
@@ -220,7 +218,7 @@ struct console hvc_con_driver = {
 };
 
 /*
- * Early console initialization.  Preceeds driver initialization.
+ * Early console initialization.  Precedes driver initialization.
  *
  * (1) we are first, and the user specified another driver
  * -- index will remain -1
@@ -257,7 +255,7 @@ int hvc_instantiate(uint32_t vtermno, int index, struct hv_ops *ops)
         if (vtermnos[index] != -1)
                 return -1;
 
-        /* make sure no no tty has been registerd in this index */
+        /* make sure no no tty has been registered in this index */
         hp = hvc_get_by_index(index);
         if (hp) {
                 kobject_put(&hp->kobj);
@@ -267,7 +265,7 @@ int hvc_instantiate(uint32_t vtermno, int index, struct hv_ops *ops)
         vtermnos[index] = vtermno;
         cons_ops[index] = ops;
 
-        /* reserve all indices upto and including this index */
+        /* reserve all indices up to and including this index */
         if (last_hvc < index)
                 last_hvc = index;
 
@@ -528,7 +526,7 @@ static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count
 
 /*
  * This is actually a contract between the driver and the tty layer outlining
- * how much write room the driver can guarentee will be sent OR BUFFERED.  This
+ * how much write room the driver can guarantee will be sent OR BUFFERED.  This
  * driver MUST honor the return value.
  */
 static int hvc_write_room(struct tty_struct *tty)
@@ -550,6 +548,18 @@ static int hvc_chars_in_buffer(struct tty_struct *tty)
         return hp->n_outbuf;
 }
 
+/*
+ * timeout will vary between the MIN and MAX values defined here.  By default
+ * and during console activity we will use a default MIN_TIMEOUT of 10.  When
+ * the console is idle, we increase the timeout value on each pass through
+ * msleep until we reach the max.  This may be noticeable as a brief (average
+ * one second) delay on the console before the console responds to input when
+ * there has been no input for some time.
+ */
+#define MIN_TIMEOUT             (10)
+#define MAX_TIMEOUT             (2000)
+static u32 timeout = MIN_TIMEOUT;
+
 #define HVC_POLL_READ   0x00000001
 #define HVC_POLL_WRITE  0x00000002
 
@@ -642,9 +652,14 @@ static int hvc_poll(struct hvc_struct *hp)
  bail:
         spin_unlock_irqrestore(&hp->lock, flags);
 
-        if (read_total)
+        if (read_total) {
+                /* Activity is occurring, so reset the polling backoff value to
+                   a minimum for performance. */
+                timeout = MIN_TIMEOUT;
+
                 tty_flip_buffer_push(tty);
-        
+        }
+
         return poll_mask;
 }
 
@@ -688,8 +703,12 @@ int khvcd(void *unused)
                 if (!hvc_kicked) {
                         if (poll_mask == 0)
                                 schedule();
-                        else
-                                msleep_interruptible(TIMEOUT);
+                        else {
+                                if (timeout < MAX_TIMEOUT)
+                                        timeout += (timeout >> 6) + 1;
+
+                                msleep_interruptible(timeout);
+                        }
                 }
                 __set_current_state(TASK_RUNNING);
         } while (!kthread_should_stop());
@@ -794,7 +813,7 @@ int __devexit hvc_remove(struct hvc_struct *hp)
 
         /*
          * We 'put' the instance that was grabbed when the kobject instance
-         * was intialized using kobject_init().  Let the last holder of this
+         * was initialized using kobject_init().  Let the last holder of this
          * kobject cause it to be removed, which will probably be the tty_hangup
          * below.
          */
@@ -850,7 +869,7 @@ int __init hvc_init(void)
 }
 module_init(hvc_init);
 
-/* This isn't particularily necessary due to this being a console driver
+/* This isn't particularly necessary due to this being a console driver
  * but it is nice to be thorough.
  */
 static void __exit hvc_exit(void)