From: Dominik Brodowski <linux@dominikbrodowski.net>
To: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: Andrew Morton <akpm@osdl.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Len Brown <len.brown@intel.com>
Subject: Re: [PATCH] acpi-cpufreq: Remove P-state read after a P-state write in normal path
Date: Sun, 28 Aug 2005 20:09:41 +0200 [thread overview]
Message-ID: <20050828180941.GB28994@isilmar.linta.de> (raw)
In-Reply-To: <20050826171052.B27226@unix-os.sc.intel.com>
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
next prev parent reply other threads:[~2005-08-28 18:09 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-08-27 0:10 Venkatesh Pallipadi
2005-08-28 18:09 ` Dominik Brodowski [this message]
2005-08-29 18:03 ` Venkatesh Pallipadi
2005-09-01 8:48 ` Dominik Brodowski
2005-08-27 2:27 Brown, Len
2005-09-01 18:44 Brown, Len
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