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

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.

TAMUKI Shoichi

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