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authorAlan Stern <stern@rowland.harvard.edu>2007-03-20 19:03:31 +0100
committerJiri Kosina <jkosina@suse.cz>2007-04-11 10:36:02 +0200
commit5e2a55f25d255a356bdaf2cb04c71b8d76c307a8 (patch)
tree70321ca66f373922bb722f81b315e08b510a826d
parent48b4554aca28f721d3dfbab077c05032b3d1cd31 (diff)
USB HID: fix retry & reset logic
The USB HID driver fails to reset its error-retry timeout when there has been a long time interval between I/O errors with no successful URB completions in the meantime. As a result, the very next error would trigger an immediate reset, even if it was a chance event occurring long after the previous error. More USB keyboards and mice than one might expect end up getting I/O errors. Almost always this results from hardware problems of one sort of another. For example, people attach the device to a USB extension cable, which degrades the signal. Or they simply have poor quality cables to begin with. Or they use a KVM switch which doesn't handle USB messages correctly. Etc... There have been reports from several users in which these I/O errors would occur more or less randomly, at intervals ranging from seconds to minutes. The error-handling code in hid-core.c was originally meant for situations where a single outage would persist for a few hundred ms (electromagnetic interference, for example). It didn't work right when these more sporadic errors occurred, because of a flaw in the logic which this patch fixes. This patch (as873) fixes that oversight. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
-rw-r--r--drivers/hid/usbhid/hid-core.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c
index 7c0fc11e972..35a41e60f54 100644
--- a/drivers/hid/usbhid/hid-core.c
+++ b/drivers/hid/usbhid/hid-core.c
@@ -554,6 +554,11 @@ static void hid_io_error(struct hid_device *hid)
if (usb_get_intfdata(usbhid->intf) == NULL)
goto done;
+ /* If it has been a while since the last error, we'll assume
+ * this a brand new error and reset the retry timeout. */
+ if (time_after(jiffies, usbhid->stop_retry + HZ/2))
+ usbhid->retry_delay = 0;
+
/* When an error occurs, retry at increasing intervals */
if (usbhid->retry_delay == 0) {
usbhid->retry_delay = 13; /* Then 26, 52, 104, 104, ... */