add uhci_hcd bug to README.md

[evhz] / README.md

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-evhz
-====
+# evhz
 
-Display the current mouse refresh rate under evdev linux system.
+Display the current mouse refresh rate under linux with evdev
+
+For information about polling rate, see https://wiki.archlinux.org/index.php/Mouse_Polling_Rate
+
+The program is just evhz.c. Compile and run:
+
+    gcc -o evhz evhz.c
+    sudo ./evhz
+
+Nonverbose mode = -n
+
+There exists a kernel bug for USB ports which use the uhci_hcd driver,
+where a 1000 hz mouse will only read at 500hz, causing jittering:
+https://bugzilla.kernel.org/show_bug.cgi?id=60586. A workaround is to
+use USB ports that use the ehci-pci driver.
+
+Maintainer: Ian Kelling <ian@iankelling.org>
+
+Bugs, patches, requests, feedback are welcome.
+
+Last tested 7/2016 on Debian testing. Still working great after several
+years.