Re: [PATCH/RFC v5 01/57] leds: Add brightness_set_nonblocking op

From: Pavel Machek
Date: Wed Aug 19 2015 - 15:31:24 EST



> > >There are around 60 drivers in the other kernel subsystems that register
> > >LED class devices. If we chose the way you proposed then we would have
> > >to adjust all of them to the LED core changes, which could complicate
> > >the situation during merge window if there were other modifications in
> > >the affected drivers.
>
> You don't need to change anything, if the semantics of
> brightness_set() does not change. All current drivers don't
> sleep. They use a work queue if needed to ensure they don't
> sleep. Hence they are correct.

Exactly. As you explain above, there are 60 reasons not to change
existing semantics.

> By adding a new operation, brightness_set_blocking(), you can strip
> out this work queue and move to the new op member one driver at a
> time. And you can take as long as you want doing this. No flag day
> when an API suddenly means something totally different.

Yes please.

Pavel
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