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From: Ashwin Chaugule <ashwin.chaugule@linaro.org>
To: Dirk Brandewie <dirk.brandewie@gmail.com>
Cc: Viresh Kumar <viresh.kumar@linaro.org>,
	"rwells@codeaurora.org" <rwells@codeaurora.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	"linaro-acpi@lists.linaro.org" <linaro-acpi@lists.linaro.org>,
	"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
	Catalin Marinas <Catalin.Marinas@arm.com>,
	Linda Knippers <linda.knippers@hp.com>
Subject: Re: [RFC PATCH v2 2/3] CPPC as a PID controller backend
Date: Thu, 9 Oct 2014 13:16:34 -0400	[thread overview]
Message-ID: <CAJ5Y-eZjBSP3eTs9QVBaaLskoL8HPgCCG0ArkgcpMLcubJAg5A@mail.gmail.com> (raw)
In-Reply-To: <5436B655.6090403@gmail.com>

Hi Dirk,

On 9 October 2014 12:22, Dirk Brandewie <dirk.brandewie@gmail.com> wrote:
> On 10/08/2014 01:11 PM, Ashwin Chaugule wrote:
>
>> +static int __init acpi_pid_init(void)
>> +{
>> +       int cpu, rc = 0;
>> +
>
>
> You should add a check here to not bind to Intel CPU. The CPPC interface
> was created to provided an ACPI interface to to hardware controlled P states
> (HWP) described in Volume 3 section 14.4 of the Intel SDM.
> intel_pstate will be enabling HWP by controlling the MSRs directly and
> not using CPPC.
>
> Adding this check will keep us from having to fight load order since
> this driver and intel_pstate are at the same init level.

Do you have a recommendation for how to check for such CPUs? Would it
make sense to deselect this driver if intel_pstate is chosen at
compile time instead?

Thanks,
Ashwin

  reply	other threads:[~2014-10-09 17:16 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-10-08 20:11 [RFC PATCH v2 0/3] CPPC as PID backend Ashwin Chaugule
2014-10-08 20:11 ` [RFC PATCH v2 1/3] PCC HACKS: Update PCC comm region with MSR data Ashwin Chaugule
2014-10-08 20:11 ` [RFC PATCH v2 2/3] CPPC as a PID controller backend Ashwin Chaugule
2014-10-09 16:22   ` Dirk Brandewie
2014-10-09 17:16     ` Ashwin Chaugule [this message]
2014-10-09 17:40       ` Dirk Brandewie
2014-10-09 18:18         ` Ashwin Chaugule
2014-10-17 13:58   ` Ashwin Chaugule
2014-10-08 20:11 ` [RFC PATCH v2 3/3] CPPC HACKS Ashwin Chaugule

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