Re: [PATCH] cpuidle: kirkwood: Move out of mach directory, add DT.

[Santosh Shilimkar <santosh.shilimkar-l0cyMroinI0@public.gmane.org>]

On Friday 28 December 2012 11:26 PM, Andrew Lunn wrote:
>> Is this single CPU or multi-cpu machine ?
>
> Its a uniprocessor.
>
That should work then.

>> Even though the cpu_do_idle()
>> has just couple of instructions, there can be lot more happening in
>> background especially with multi masters system. It might be safe if the
>> single CPU is the only master accessing DDR. In multi-master, multi-CPU
>> scenario though it can't work reliably.
>
> There are DMA engines which could be active, moving stuff into/out of
> memory.
>
Sure but you must be stopping DMA before entering idle where DDR can 
enter into self-refresh otherwise DMA transfer will be aborted. DDR
controller also can take care of such a scenario by not entering into
self refresh when DMA is active and self refresh command is issued.

> Having said that, this code is not new, it is just getting a new home.
> There has not been problems before. Having this 256 cycle delay etc,
> suggests the hardware design is robust.
>
Thanks for information that it is robust and working well. I was just
curious having faced some issues on this topic in past.

Regards
Santosh