From 0cfbd328d60f85b0dcf66df61a3615e9a8e5d4e4 Mon Sep 17 00:00:00 2001 From: Michal Sojka Date: Wed, 24 Sep 2014 22:43:21 +0200 Subject: usb: Add LED triggers for USB activity MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 --- drivers/usb/common/Makefile | 1 + 1 file changed, 1 insertion(+) (limited to 'drivers/usb/common/Makefile') diff --git a/drivers/usb/common/Makefile b/drivers/usb/common/Makefile index 052c12069c24..ca2f8bd0e431 100644 --- a/drivers/usb/common/Makefile +++ b/drivers/usb/common/Makefile @@ -4,5 +4,6 @@ obj-$(CONFIG_USB_COMMON) += usb-common.o usb-common-y += common.o +usb-common-$(CONFIG_USB_LED_TRIG) += led.o obj-$(CONFIG_USB_OTG_FSM) += usb-otg-fsm.o -- cgit v1.3.1