[PATCH 01/17] leds: create a trigger for CPU activity

On Wed, 6 Jul 2011, Russell King - ARM Linux wrote:

On Wed, Jul 06, 2011 at 09:16:47PM +0800, Eric Miao wrote:

quoted

On Wed, Jul 6, 2011 at 8:34 PM, Bryan Wu [off-list ref] wrote:

quoted

+ ? ? ? switch (ledevt) {
+ ? ? ? case CPU_LED_START:
+ ? ? ? case CPU_LED_IDLE_START:
+ ? ? ? ? ? ? ? /* Will turn the LED on, max brightness */
+ ? ? ? ? ? ? ? if (trigdata->led)
+ ? ? ? ? ? ? ? ? ? ? ? led_set_brightness(trigdata->led,
+ ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?trigdata->led->max_brightness);
+ ? ? ? ? ? ? ? break;
+
+ ? ? ? case CPU_LED_STOP:
+ ? ? ? case CPU_LED_IDLE_END:
+ ? ? ? case CPU_LED_HALTED:
+ ? ? ? ? ? ? ? /* Will turn the LED off */
+ ? ? ? ? ? ? ? if (trigdata->led)
+ ? ? ? ? ? ? ? ? ? ? ? led_set_brightness(trigdata->led, LED_OFF);
+ ? ? ? ? ? ? ? break;
+
+ ? ? ? default:
+ ? ? ? ? ? ? ? /* Will leave the LED as it is */
+ ? ? ? ? ? ? ? break;
+ ? ? ? }
+}

I'm a bit worrying about the LED brightness hardcoded here, what if
a platform requires different behavior, e.g. LED_OFF when IDLE_START.

Indeed - there are platforms (Netwinder, Assabet etc) which use LED=ON
to mean that the system is not idle - and also turn the LED on when
halted.

What about simply setting active_low to 1 in the struct gpio_led 
instance for those particular LEDs (or invert it if it is already set)?


Nicolas