From: Michal Sojka Date: Wed, 24 Sep 2014 20:43:21 +0000 (+0200) Subject: usb: Add LED triggers for USB activity X-Git-Tag: fixes-for-v3.18-merge-window~16^2~14 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0cfbd328d60f85b0dcf66df61a3615e9a8e5d4e4;p=pandora-kernel.git usb: Add LED triggers for USB activity With this patch, USB activity can be signaled by blinking a LED. There are two triggers, one for activity on USB host and one for USB gadget. Both triggers should work with all host/device controllers. Tested only with musb. Performace: I measured performance overheads on ARM Cortex-A8 (TI AM335x) running on 600 MHz. Duration of usb_led_activity(): - with no LED attached to the trigger: 2 ± 1 µs - with one GPIO LED attached to the trigger: 2 ± 1 µs or 8 ± 2 µs (two peaks in histogram) Duration of functions calling usb_led_activity() (with this patch applied and no LED attached to the trigger): - __usb_hcd_giveback_urb(): 10 - 25 µs - usb_gadget_giveback_request(): 2 - 6 µs Signed-off-by: Michal Sojka Acked-by: Felipe Balbi Tested-by: Felipe Balbi Signed-off-by: Greg Kroah-Hartman --- Reading git-diff-tree failed