HID: usbhid: defer LED setting to a workqueue

Defer LED setting action to a workqueue.
This is more likely to send all LED change events in a single URB.

Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
Acked-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

4 files changed, 82 insertions, 11 deletions

diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
index b9b8c75a6f9a..c6ee632bfd68 100644
--- a/drivers/hid/hid-input.c
+++ b/drivers/hid/hid-input.c
@@ -976,6 +976,48 @@ int hidinput_find_field(struct hid_device *hid, unsigned int type, unsigned int
 }
 EXPORT_SYMBOL_GPL(hidinput_find_field);
 
+struct hid_field *hidinput_get_led_field(struct hid_device *hid)
+{
+        struct hid_report *report;
+        struct hid_field *field;
+        int i, j;
+
+        list_for_each_entry(report,
+                            &hid->report_enum[HID_OUTPUT_REPORT].report_list,
+                            list) {
+                for (i = 0; i < report->maxfield; i++) {
+                        field = report->field[i];
+                        for (j = 0; j < field->maxusage; j++)
+                                if (field->usage[j].type == EV_LED)
+                                        return field;
+                }
+        }
+        return NULL;
+}
+EXPORT_SYMBOL_GPL(hidinput_get_led_field);
+
+unsigned int hidinput_count_leds(struct hid_device *hid)
+{
+        struct hid_report *report;
+        struct hid_field *field;
+        int i, j;
+        unsigned int count = 0;
+
+        list_for_each_entry(report,
+                            &hid->report_enum[HID_OUTPUT_REPORT].report_list,
+                            list) {
+                for (i = 0; i < report->maxfield; i++) {
+                        field = report->field[i];
+                        for (j = 0; j < field->maxusage; j++)
+                                if (field->usage[j].type == EV_LED &&
+                                    field->value[j])
+                                        count += 1;
+                }
+        }
+        return count;
+}
+EXPORT_SYMBOL_GPL(hidinput_count_leds);
+
 static int hidinput_open(struct input_dev *dev)
 {
         struct hid_device *hid = input_get_drvdata(dev);
diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c
index 719f6b02fab1..5bf91dbad59d 100644
--- a/drivers/hid/usbhid/hid-core.c
+++ b/drivers/hid/usbhid/hid-core.c
@@ -602,6 +602,30 @@ void usbhid_submit_report(struct hid_device *hid, struct hid_report *report, uns
 }
 EXPORT_SYMBOL_GPL(usbhid_submit_report);
 
+/* Workqueue routine to send requests to change LEDs */
+static void hid_led(struct work_struct *work)
+{
+        struct usbhid_device *usbhid =
+                container_of(work, struct usbhid_device, led_work);
+        struct hid_device *hid = usbhid->hid;
+        struct hid_field *field;
+        unsigned long flags;
+
+        field = hidinput_get_led_field(hid);
+        if (!field) {
+                hid_warn(hid, "LED event field not found\n");
+                return;
+        }
+
+        spin_lock_irqsave(&usbhid->lock, flags);
+        if (!test_bit(HID_DISCONNECTED, &usbhid->iofl)) {
+                usbhid->ledcount = hidinput_count_leds(hid);
+                hid_dbg(usbhid->hid, "New ledcount = %u\n", usbhid->ledcount);
+                __usbhid_submit_report(hid, field->report, USB_DIR_OUT);
+        }
+        spin_unlock_irqrestore(&usbhid->lock, flags);
+}
+
 static int usb_hidinput_input_event(struct input_dev *dev, unsigned int type, unsigned int code, int value)
 {
         struct hid_device *hid = input_get_drvdata(dev);
@@ -621,17 +645,15 @@ static int usb_hidinput_input_event(struct input_dev *dev, unsigned int type, un
                 return -1;
         }
 
+        spin_lock_irqsave(&usbhid->lock, flags);
         hid_set_field(field, offset, value);
-        if (value) {
-                spin_lock_irqsave(&usbhid->lock, flags);
-                usbhid->ledcount++;
-                spin_unlock_irqrestore(&usbhid->lock, flags);
-        } else {
-                spin_lock_irqsave(&usbhid->lock, flags);
-                usbhid->ledcount--;
-                spin_unlock_irqrestore(&usbhid->lock, flags);
-        }
-        usbhid_submit_report(hid, field->report, USB_DIR_OUT);
+        spin_unlock_irqrestore(&usbhid->lock, flags);
+
+        /*
+         * Defer performing requested LED action.
+         * This is more likely gather all LED changes into a single URB.
+         */
+        schedule_work(&usbhid->led_work);
 
         return 0;
 }
@@ -1126,7 +1148,7 @@ static void usbhid_stop(struct hid_device *hid)
                 return;
 
         clear_bit(HID_STARTED, &usbhid->iofl);
-        spin_lock_irq(&usbhid->lock);   /* Sync with error handler */
+        spin_lock_irq(&usbhid->lock);   /* Sync with error and led handlers */
         set_bit(HID_DISCONNECTED, &usbhid->iofl);
         spin_unlock_irq(&usbhid->lock);
         usb_kill_urb(usbhid->urbin);
@@ -1260,6 +1282,8 @@ static int usbhid_probe(struct usb_interface *intf, const struct usb_device_id *
         setup_timer(&usbhid->io_retry, hid_retry_timeout, (unsigned long) hid);
         spin_lock_init(&usbhid->lock);
 
+        INIT_WORK(&usbhid->led_work, hid_led);
+
         ret = hid_add_device(hid);
         if (ret) {
                 if (ret != -ENODEV)
@@ -1292,6 +1316,7 @@ static void hid_cancel_delayed_stuff(struct usbhid_device *usbhid)
 {
         del_timer_sync(&usbhid->io_retry);
         cancel_work_sync(&usbhid->reset_work);
+        cancel_work_sync(&usbhid->led_work);
 }
 
 static void hid_cease_io(struct usbhid_device *usbhid)
diff --git a/drivers/hid/usbhid/usbhid.h b/drivers/hid/usbhid/usbhid.h
index 2d8957c11d2d..cb8f703efde5 100644
--- a/drivers/hid/usbhid/usbhid.h
+++ b/drivers/hid/usbhid/usbhid.h
@@ -96,6 +96,8 @@ struct usbhid_device {
         struct work_struct reset_work;                                  /* Task context for resets */
         wait_queue_head_t wait;                                         /* For sleeping */
         int ledcount;                                                   /* counting the number of active leds */
+
+        struct work_struct led_work;                                    /* Task context for setting LEDs */
 };
 
 #define hid_to_usb_dev(hid_dev) \
diff --git a/include/linux/hid.h b/include/linux/hid.h
index 7f344c3da767..999a54c72b20 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -727,6 +727,8 @@ extern void hidinput_disconnect(struct hid_device *);
 int hid_set_field(struct hid_field *, unsigned, __s32);
 int hid_input_report(struct hid_device *, int type, u8 *, int, int);
 int hidinput_find_field(struct hid_device *hid, unsigned int type, unsigned int code, struct hid_field **field);
+struct hid_field *hidinput_get_led_field(struct hid_device *hid);
+unsigned int hidinput_count_leds(struct hid_device *hid);
 void hid_output_report(struct hid_report *report, __u8 *data);
 struct hid_device *hid_allocate_device(void);
 struct hid_report *hid_register_report(struct hid_device *device, unsigned type, unsigned id);