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

On Fri, Aug 26, 2005 at 05:10:52PM -0700, Venkatesh Pallipadi wrote:
> /*
> - * Then we read the 'status_register' and compare the value with the
> - * target state's 'status' to make sure the transition was successful.
> - * Note that we'll poll for up to 1ms (100 cycles of 10us) before
> - * giving up.
> + * Assume the write went through when acpi_pstate_strict is not used.
> + * As read status_register is an expensive operation and there
> + * are no specific error cases where an IO port write will fail.
> */

Well, the IO port write itself might not fail, but the transition itself --
and we're reading the _status_ register here, not the control register where
we've written to. And 8.4.4.1 of ACPI-sepc 3.0 does specifically mention
that transitions _can_ fail, so I think we should handle this possibility.

Dominik
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