[PATCH v4] USB: HID: random timeout failures tackle try.

* [PATCH v4] USB: HID: random timeout failures tackle try.
@ 2020-02-04 14:46 Lauri Jakku
  2020-02-04 14:57 ` Alan Stern
  0 siblings, 1 reply; 3+ messages in thread
From: Lauri Jakku @ 2020-02-04 14:46 UTC (permalink / raw)
  To: oneukum, benjamin.tissoires
  Cc: jikos, linux-input, gregkh, linux-usb, Lauri Jakku

-- v1 ------------------------------------------------------------
send, 20ms apart, control messages, if error is timeout.

There is multiple reports of random behaviour of USB HID devices.

I have mouse that acts sometimes quite randomly, I debugged with
logs others have published that there is HW timeouts that leave
device in state that it is errorneus.

To fix this I introduced retry mechanism in root of USB HID drivers.

Fix does not slow down operations at all if there is no -ETIMEDOUT
got from control message sending. If there is one, then sleep 20ms
and try again. Retry count is 20 witch translates maximium of 400ms
before giving up.

NOTE: This does not sleep anymore then before, if all is golden.

-- v2 ------------------------------------------------------------

If there is timeout, then sleep 20ms and try again. Retry count is 20
witch translates maximium of 400ms before giving up. If the 400ms
boundary is reached the HW is really bad.

JUST to be clear:
    This does not make USB HID devices to sleep anymore than
    before, if all is golden.

Why modify usb-hid-core: No need to modify driver by driver.

-- v3 ------------------------------------------------------------

Timeout given is divided by 100, but taken care that it is always
at least 10ms.

so total time in common worst-case-scenario is:

 sleep of 20ms + common timeout divided by 100 (50ms) makes
 70ms per loop, 20 loops => 1.4sec .

-- v4 ------------------------------------------------------------
No changes in code, just elaborating what is done in v[1,2,3].

Signed-off-by: Lauri Jakku <lja@iki.fi>
---
 drivers/usb/core/message.c | 55 ++++++++++++++++++++++++++++++++++----
 1 file changed, 50 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
index 5adf489428aa..614c762989ab 100644
--- a/drivers/usb/core/message.c
+++ b/drivers/usb/core/message.c
@@ -20,6 +20,7 @@
 #include <linux/usb/hcd.h>	/* for usbcore internals */
 #include <linux/usb/of.h>
 #include <asm/byteorder.h>
+#include <linux/errno.h>
 
 #include "usb.h"
 
@@ -137,7 +138,10 @@ int usb_control_msg(struct usb_device *dev, unsigned int pipe, __u8 request,
 		    __u16 size, int timeout)
 {
 	struct usb_ctrlrequest *dr;
-	int ret;
+	int ret = -ETIMEDOUT;
+
+	/* retry_cnt * 20ms, max retry time set to 400ms */
+	int retry_cnt = 20;
 
 	dr = kmalloc(sizeof(struct usb_ctrlrequest), GFP_NOIO);
 	if (!dr)
@@ -149,11 +153,52 @@ int usb_control_msg(struct usb_device *dev, unsigned int pipe, __u8 request,
 	dr->wIndex = cpu_to_le16(index);
 	dr->wLength = cpu_to_le16(size);
 
-	ret = usb_internal_control_msg(dev, pipe, dr, data, size, timeout);
+	do {
+		ret = usb_internal_control_msg(dev,
+					pipe,
+					dr,
+					data,
+					size,
+					timeout);
+
+		/*
+		 * Linger a bit, prior to the next control message
+		 * or if return value is timeout, but do try few
+		 * times (max 400ms) before quitting. Adapt timeout
+		 * to be smaller when we have timeout'd first time.
+		 */
+		if (dev->quirks & USB_QUIRK_DELAY_CTRL_MSG)
+			msleep(200);
+		else if (ret == -ETIMEDOUT) {
+			static timeout_happened = 0;
+
+			if ( ! timeout_happened ) {
+				timeout_happened = 1;
+
+				/* 
+				 * If timeout is given, divide it
+				 * by 100, if not, put 10ms timeout.
+				 * 
+				 * Then safeguard: if timeout is under
+				 * 10ms, make timeout to be 10ms.
+				 */
+
+				if (timeout > 0)
+					timeout /= 100;
+				else
+					timeout = 10;
+
+				if (timeout < 10)
+					timeout = 10;
+
+			}
+
+			msleep(20);
+		}
+
+		/* Loop while timeout, max loops: retry_cnt times. */
+	} while ((retry_cnt-- > 0) && (ret == -ETIMEDOUT));
 
-	/* Linger a bit, prior to the next control message. */
-	if (dev->quirks & USB_QUIRK_DELAY_CTRL_MSG)
-		msleep(200);
 
 	kfree(dr);
 
-- 
2.25.0


^ permalink raw reply related	[flat|nested] 3+ messages in thread