Re: [PATCH] acpi-cpufreq: Remove P-state read after a P-state write in normal path

[Dominik Brodowski <linux@dominikbrodowski.net>]

Hi,

On Mon, Aug 29, 2005 at 11:03:57AM -0700, Venkatesh Pallipadi wrote:
> Yes. ACPI spec says transitions can fail. But, it doesn't fail often in 
> practise. And even if it fails, I think, we should handle it without this 
> read os STATUS register.

How can we handle it, if we do not even know that it failed? How should the
user recognize something is broken?

> The speedstep-centrino driver, which does similar
> thing as acpi-cpufreq, does not do this status check after control MSR write.
> We can skip the read of STATUS in cpi-cpufreq in a similar way. No?

Well, regarding speedstep-centrino, it is news to me that the MSR write can
fail... if it can fail, we should check for it.

> And reading the STATUS in a loop should go away. I don't see that it being 
> mentioned in ACPI spec. The 1mS loop seems totally redundant.

It looks to me as somebody had experienced that the transition only
succeeded after waiting for some time.

But well, as you do know the ACPI spec better than I do, I'll accept your
evaluation that this patch won't cause any trouble.

	Dominik
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/