Messages in this thread | | | Subject | Re: [PATCH v5 1/8] leds: add support for hardware driven LEDs | From | Randy Dunlap <> | Date | Fri, 12 Nov 2021 17:04:20 -0800 |
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On 11/12/21 7:35 AM, Ansuel Smith wrote: > diff --git a/Documentation/leds/leds-class.rst b/Documentation/leds/leds-class.rst > index cd155ead8703..e5d266919a19 100644 > --- a/Documentation/leds/leds-class.rst > +++ b/Documentation/leds/leds-class.rst > @@ -169,6 +169,38 @@ Setting the brightness to zero with brightness_set() callback function > should completely turn off the LED and cancel the previously programmed > hardware blinking function, if any. > > +Hardware driven LEDs > +=================================== > + > +Some LEDs can be driven by hardware (for example an LED connected to > +an ethernet PHY or an ethernet switch can be configured to blink on activity on > +the network, which in software is done by the netdev trigger). > + > +To do such offloading, LED driver must support this and a supported trigger must > +be used. > + > +LED driver should declare the correct control mode supported and should set > +the LED_SOFTWARE_CONTROLLED or LED_HARDWARE_CONTROLLED bit in the flags > +parameter. > +The trigger will check these bits and fail to activate if the control mode > +is not supported. By default if a LED driver doesn't declare a control mode,
if an LED driver
> +bit LED_SOFTWARE_CONTROLLED is assumed and set. > + > +The LED must implement 3 main APIs: > +- hw_control_status(): This asks the LED driver if hardware mode is enabled > + or not. > +- hw_control_start(): This will simply enable the hardware mode for the LED > + and the LED driver should reset any active blink_mode. > +- hw_control_stop(): This will simply disable the hardware mode for the LED. > + It's advised to the driver to put the LED in the old state but this is not > + enforced and putting the LED off is also accepted. > + > +If LED_HARDWARE_CONTROLLED bit is the only control mode set (LED_SOFTWARE_CONTROLLED > +not set) set hw_control_status/start/stop is optional as the LED supports only
^^^ is that an extra "set"? I can't quite read this sentence.
And it would be better with a comma added, like so:
not set),
> +hardware mode and any software only trigger will reject activation.
software-only
> + > +On init an LED driver that support a hardware mode should reset every blink mode
supports
> +set by default.
-- ~Randy
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