Input: evdev - Add the events() callback

By sending a full frame of events at the same time, the irqsoff
latency at heavy load is brought down from 200 us to 100 us.

Cc: Daniel Kurtz <djkurtz@chromium.org>
Tested-by: Benjamin Tissoires <benjamin.tissoires@enac.fr>
Tested-by: Ping Cheng <pingc@wacom.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Henrik Rydberg <rydberg@euromail.se>

1 files changed, 47 insertions, 21 deletions

diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
index a0692c551be5..118d0300f1fb 100644
--- a/drivers/input/evdev.c
+++ b/drivers/input/evdev.c
@@ -54,16 +54,9 @@ struct evdev_client {
 static struct evdev *evdev_table[EVDEV_MINORS];
 static DEFINE_MUTEX(evdev_table_mutex);
 
-static void evdev_pass_event(struct evdev_client *client,
-                             struct input_event *event,
-                             ktime_t mono, ktime_t real)
+static void __pass_event(struct evdev_client *client,
+                         const struct input_event *event)
 {
-        event->time = ktime_to_timeval(client->clkid == CLOCK_MONOTONIC ?
-                                        mono : real);
-
-        /* Interrupts are disabled, just acquire the lock. */
-        spin_lock(&client->buffer_lock);
-
         client->buffer[client->head++] = *event;
         client->head &= client->bufsize - 1;
 
@@ -86,42 +79,74 @@ static void evdev_pass_event(struct evdev_client *client,
                 client->packet_head = client->head;
                 kill_fasync(&client->fasync, SIGIO, POLL_IN);
         }
+}
+
+static void evdev_pass_values(struct evdev_client *client,
+                        const struct input_value *vals, unsigned int count,
+                        ktime_t mono, ktime_t real)
+{
+        struct evdev *evdev = client->evdev;
+        const struct input_value *v;
+        struct input_event event;
+        bool wakeup = false;
+
+        event.time = ktime_to_timeval(client->clkid == CLOCK_MONOTONIC ?
+                                      mono : real);
+
+        /* Interrupts are disabled, just acquire the lock. */
+        spin_lock(&client->buffer_lock);
+
+        for (v = vals; v != vals + count; v++) {
+                event.type = v->type;
+                event.code = v->code;
+                event.value = v->value;
+                __pass_event(client, &event);
+                if (v->type == EV_SYN && v->code == SYN_REPORT)
+                        wakeup = true;
+        }
 
         spin_unlock(&client->buffer_lock);
+
+        if (wakeup)
+                wake_up_interruptible(&evdev->wait);
 }
 
 /*
- * Pass incoming event to all connected clients.
+ * Pass incoming events to all connected clients.
  */
-static void evdev_event(struct input_handle *handle,
-                        unsigned int type, unsigned int code, int value)
+static void evdev_events(struct input_handle *handle,
+                         const struct input_value *vals, unsigned int count)
 {
         struct evdev *evdev = handle->private;
         struct evdev_client *client;
-        struct input_event event;
         ktime_t time_mono, time_real;
 
         time_mono = ktime_get();
         time_real = ktime_sub(time_mono, ktime_get_monotonic_offset());
 
-        event.type = type;
-        event.code = code;
-        event.value = value;
-
         rcu_read_lock();
 
         client = rcu_dereference(evdev->grab);
 
         if (client)
-                evdev_pass_event(client, &event, time_mono, time_real);
+                evdev_pass_values(client, vals, count, time_mono, time_real);
         else
                 list_for_each_entry_rcu(client, &evdev->client_list, node)
-                        evdev_pass_event(client, &event, time_mono, time_real);
+                        evdev_pass_values(client, vals, count,
+                                          time_mono, time_real);
 
         rcu_read_unlock();
+}
 
-        if (type == EV_SYN && code == SYN_REPORT)
-                wake_up_interruptible(&evdev->wait);
+/*
+ * Pass incoming event to all connected clients.
+ */
+static void evdev_event(struct input_handle *handle,
+                        unsigned int type, unsigned int code, int value)
+{
+        struct input_value vals[] = { { type, code, value } };
+
+        evdev_events(handle, vals, 1);
 }
 
 static int evdev_fasync(int fd, struct file *file, int on)
@@ -1050,6 +1075,7 @@ MODULE_DEVICE_TABLE(input, evdev_ids);
 
 static struct input_handler evdev_handler = {
         .event          = evdev_event,
+        .events         = evdev_events,
         .connect        = evdev_connect,
         .disconnect     = evdev_disconnect,
         .fops           = &evdev_fops,