Re: [PATCH] panic: keep blinking in spite of long spin timer mode

[TAMUKI Shoichi <tamuki@linet.gr.jp>]

Hello,

On Wed, 2 Jun 2010 11:34:46 -0700 Andrew Morton wrote:

> The whole panic-blink setup seems rather poorly thought out.
> 
> Would it not be better if a call to (*panic_blink)() were to simply set
> the state of the LED and then return?  So callers can do
> 
> 	int state = 0;
> 
> 	for ( ; ; ) {
> 		(*panic_blink)(state);
> 		state ^= 1;
> 		mdelay(MSEC_PER_SEC);
> 	}
> 
> ?

Your proposal is rather simpler than the current patch, indeed.

I carefully went into the proposal:

  - With this implementation, the time to call to mdelay() needs to be
    variable in order to change the speed of blinking.
  - It is not desirable that the period to call to touch_nmi_watchdog()
    or touch_softlockup_watchdog() depends on the speed of blinking.
  - We would like to leave the room that can be implemented as not only
    a simple blinking but also as a so-called morse blinking which con-
    tains useful information when kernel panics.

That being the reason, I will keep the current implementation that the
time to call mdelay() is a short constant (as 1ms usually).

BTW, there are some sanity checks or something in panic_blink_enter(),
which need not exist there, so I have moved them to appropriate place.

Thank you for the suggestion.  See you next PATCH v2.

Regards,
TAMUKI Shoichi