linux-kernel - Re: blink driver power saving

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Date:	Sun, 1 Jul 2007 15:14:25 -0700 (PDT)
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Andi Kleen <ak@...e.de>
cc:	Stephen Hemminger <shemminger@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: blink driver power saving

On Sun, 1 Jul 2007, Andi Kleen wrote:
> 
> What is so bad with it? Note it's a debugging facility and used 
> for kcrash kernels where the video output doesn't work. But they
> normally only run a few minutes to dump the previous state to disk
> and then reboot. 

It has been a total disaster from beginning to end.

It wastes power.

It hangs machines when it tries to blink.

To quote an earlier thread:

  "The driver uses panic_blink - something that we expect to work after 
   panic. It rapidly polls KBC status register to detect when it accepted 
   led command and does it without taking i8042_lock (because it may have 
   been taken before kernel panicked) so it is quite possible that that 
   interferes with atkbd operation."

and it has been confirmed to render unusable at least some thinkpads. I 
think it was Pavel who reported it last.

> But then I don't think it hurts anybody.  It's main problem
> is that it won't blink for people with USB keyboard.

No, its main problem is that PEOPLE SHOULD NOT USE IT, but it sounds cool, 
so people end up configuring the damn thing even though they shouldn't.

Which is why I think it should be marked broken.

And yes, it *does* hurt people.

		Linus
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