Revert "HID: usbhid: do not sleep when opening device"

This reverts commit d313279.

This patch causes a regression with quite a few devices, as probing fails
because of the race where the first IRQ is dropped on the floor (after
hid_device_io_start() happens, but before the 50ms timeout passess), and
report descriptor never gets parsed and populated.

As this is just a boot time micro-optimization, let's revert the
patch for 5.9 now, and fix this properly eventually for next merge
window.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=208935
Reported-by: Johannes Hirte <johannes.hirte@datenkhaos.de>
Reported-by: Marius Zachmann <mail@mariuszachmann.de>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/usbhid/hid-core.c

@@ -26,7 +26,6 @@
 #include <linux/wait.h>
 #include <linux/workqueue.h>
 #include <linux/string.h>
-#include <linux/timekeeping.h>
 
 #include <linux/usb.h>
 
@@ -96,18 +95,6 @@ static int hid_start_in(struct hid_device *hid)
 				set_bit(HID_NO_BANDWIDTH, &usbhid->iofl);
 		} else {
 			clear_bit(HID_NO_BANDWIDTH, &usbhid->iofl);
-
-			if (test_bit(HID_RESUME_RUNNING, &usbhid->iofl)) {
-				/*
-				 * In case events are generated while nobody was
-				 * listening, some are released when the device
-				 * is re-opened. Wait 50 msec for the queue to
-				 * empty before allowing events to go through
-				 * hid.
-				 */
-				usbhid->input_start_time =
-					ktime_add_ms(ktime_get_coarse(), 50);
-			}
 		}
 	}
 	spin_unlock_irqrestore(&usbhid->lock, flags);
@@ -293,23 +280,20 @@ static void hid_irq_in(struct urb *urb)
 		if (!test_bit(HID_OPENED, &usbhid->iofl))
 			break;
 		usbhid_mark_busy(usbhid);
-		if (test_bit(HID_RESUME_RUNNING, &usbhid->iofl)) {
-			if (ktime_before(ktime_get_coarse(),
-					 usbhid->input_start_time))
-				break;
-			clear_bit(HID_RESUME_RUNNING, &usbhid->iofl);
+		if (!test_bit(HID_RESUME_RUNNING, &usbhid->iofl)) {
+			hid_input_report(urb->context, HID_INPUT_REPORT,
+					 urb->transfer_buffer,
+					 urb->actual_length, 1);
+			/*
+			 * autosuspend refused while keys are pressed
+			 * because most keyboards don't wake up when
+			 * a key is released
+			 */
+			if (hid_check_keys_pressed(hid))
+				set_bit(HID_KEYS_PRESSED, &usbhid->iofl);
+			else
+				clear_bit(HID_KEYS_PRESSED, &usbhid->iofl);
 		}
-		hid_input_report(urb->context, HID_INPUT_REPORT,
-				 urb->transfer_buffer, urb->actual_length, 1);
-		/*
-		 * autosuspend refused while keys are pressed
-		 * because most keyboards don't wake up when
-		 * a key is released
-		 */
-		if (hid_check_keys_pressed(hid))
-			set_bit(HID_KEYS_PRESSED, &usbhid->iofl);
-		else
-			clear_bit(HID_KEYS_PRESSED, &usbhid->iofl);
 		break;
 	case -EPIPE:		/* stall */
 		usbhid_mark_busy(usbhid);
@@ -736,6 +720,17 @@ static int usbhid_open(struct hid_device *hid)
 
 	usb_autopm_put_interface(usbhid->intf);
 
+	/*
+	 * In case events are generated while nobody was listening,
+	 * some are released when the device is re-opened.
+	 * Wait 50 msec for the queue to empty before allowing events
+	 * to go through hid.
+	 */
+	if (res == 0)
+		msleep(50);
+
+	clear_bit(HID_RESUME_RUNNING, &usbhid->iofl);
+
  Done:
 	mutex_unlock(&usbhid->mutex);
 	return res;

drivers/hid/usbhid/usbhid.h

@@ -13,7 +13,6 @@
 
 #include <linux/types.h>
 #include <linux/slab.h>
-#include <linux/ktime.h>
 #include <linux/list.h>
 #include <linux/mutex.h>
 #include <linux/timer.h>
@@ -84,7 +83,6 @@ struct usbhid_device {
 	struct mutex mutex;						/* start/stop/open/close */
 	spinlock_t lock;						/* fifo spinlock */
 	unsigned long iofl;                                             /* I/O flags (CTRL_RUNNING, OUT_RUNNING) */
-	ktime_t input_start_time;					/* When to start handling input */
 	struct timer_list io_retry;                                     /* Retry timer */
 	unsigned long stop_retry;                                       /* Time to give up, in jiffies */
 	unsigned int retry_delay;                                       /* Delay length in ms */