From: Kevin Hilman <khilman@ti.com>
To: Vishwanath Sripathy <vishwanath.bs@ti.com>
Cc: linux-omap@vger.kernel.org, patches@linaro.org
Subject: Re: [PATCH 1/3] OMAP3 PM: Deny clock gating only for safe state
Date: Wed, 02 Mar 2011 13:11:25 -0800 [thread overview]
Message-ID: <87d3m99qiq.fsf@ti.com> (raw)
In-Reply-To: <e295d93b87df63e95a46e625d7422433@mail.gmail.com> (Vishwanath Sripathy's message of "Wed, 2 Mar 2011 22:44:46 +0530")
Vishwanath Sripathy <vishwanath.bs@ti.com> writes:
> Kevin,
>
>> -----Original Message-----
>> From: Kevin Hilman [mailto:khilman@ti.com]
>> Sent: Wednesday, March 02, 2011 2:32 AM
>> To: Vishwanath BS
>> Cc: linux-omap@vger.kernel.org; patches@linaro.org
>> Subject: Re: [PATCH 1/3] OMAP3 PM: Deny clock gating only for safe
>> state
>>
>> Vishwanath BS <vishwanath.bs@ti.com> writes:
>>
>> > Currently clock gating for MPU and core are denied whenever C1 state
>> is
>> > selected.
>>
>> Yes, that is the definition of C1.
>>
>> > It should be denied only when safe state is selected.
>>
>> Why?
> Clock gating in C1 will reduce overall power consumption and it should not
> impact any functionality as well.
Clock gating changes latencies.
>>
>> This changes the definition and behavior of C1 depending on how it is
>> entered. Not a good idea IMO.
> I thought of adding a new C state, keeping C1 definition unchanged. Then
> we will not get the real power benefit since in case of C1, clock gating
> will be prevented. Let me know if you have some suggestion.
My problem with this patch is that you make C1 have different behavior
depending on whether it is selected directly by the governor or it is
entered due to the safe state.
The motiviation for this change is not at all described in the
changelog.
Kevin
next prev parent reply other threads:[~2011-03-02 21:11 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-16 9:01 [PATCH 0/3] OMAP3 PM: CPUIdle fixes Vishwanath BS
2011-02-16 9:01 ` [PATCH 1/3] OMAP3 PM: Deny clock gating only for safe state Vishwanath BS
2011-03-01 21:01 ` Kevin Hilman
2011-03-02 17:14 ` Vishwanath Sripathy
2011-03-02 21:11 ` Kevin Hilman [this message]
2011-02-16 9:01 ` [PATCH 2/3] OMAP3 PM: Update only enabled C states Vishwanath BS
2011-02-16 9:01 ` [PATCH 3/3] OMAP36xx PM: Updated C state latencies for OMAP3630 Vishwanath BS
2011-03-01 21:45 ` Kevin Hilman
2011-03-02 17:17 ` Vishwanath Sripathy
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