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/Kconfig | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'drivers/usb/Kconfig') diff --git a/drivers/usb/Kconfig b/drivers/usb/Kconfig index cf1b19bca306..ae481c37a208 100644 --- a/drivers/usb/Kconfig +++ b/drivers/usb/Kconfig @@ -149,4 +149,14 @@ source "drivers/usb/phy/Kconfig" source "drivers/usb/gadget/Kconfig" +config USB_LED_TRIG + bool "USB LED Triggers" + depends on LEDS_CLASS && USB_COMMON && LEDS_TRIGGERS + help + This option adds LED triggers for USB host and/or gadget activity. + + Say Y here if you are working on a system with led-class supported + LEDs and you want to use them as activity indicators for USB host or + gadget. + endif # USB_SUPPORT -- cgit v1.2.1