From: pgaikwad@nvidia•com (Prashant Gaikwad)
To: linux-arm-kernel@lists•infradead.org
Subject: Device tree binding for DVFS table
Date: Thu, 12 Jul 2012 09:52:40 +0530 [thread overview]
Message-ID: <4FFE5110.8020803@nvidia.com> (raw)
In-Reply-To: <20120711134956.GB9437@tbergstrom-lnx.Nvidia.com>
On Wednesday 11 July 2012 07:19 PM, Peter De Schrijver wrote:
> On Wed, Jul 11, 2012 at 03:08:14PM +0200, ??? wrote:
>>> Hi,
>>>
>>> I am working on DT binding for Tegra DVFS.
>>>
>>> For Tegra, DVFS node mainly consists of frequency and voltage pairs.
>>> Frequency in the pair may change for different process. E.g. for process
>>> 1 CPU clock frequency could be 900MHz at 1V while for process 2 it could
>>> be 1GHz at 1V.
>>> Tegra uses vendor specific ids to identify the correct frequency table.
>> Hello,
>>
>> It seems that in the example, the values in "voltage-array" and
>> "frequencies" are switched.
>>
>> Anyway, what about SoCs that reads information from IEM (or any other module)
>> to measure gate delays or some other value to set the appriorate voltage values
>> for every possible frequency? I remember some of Exynos SoCs have been doing
>> it; dynamically measure the characteristics at boot-up time and apply voltages
>> accordingly; they couldn't identify it based on the chip-id or simply by reading
>> a single register.
>>
>
> But in that case you would have a nominal voltage for each OPP which gets
> adjusted at boottime or runtime depending on the exact silicon characteristics?
> I would say the DT binding should then specify 1 table with the nominal values
> and leave the dynamics to the driver.
It makes sense or is it different than this?
> Cheers,
>
> Peter.
>
next prev parent reply other threads:[~2012-07-12 4:22 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-11 13:08 Device tree binding for DVFS table 함명주
2012-07-11 13:49 ` Peter De Schrijver
2012-07-11 13:49 ` Peter De Schrijver
2012-07-12 4:22 ` Prashant Gaikwad [this message]
-- strict thread matches above, loose matches on Subject: below --
2012-07-11 12:56 Prashant Gaikwad
2012-07-11 14:03 ` Rob Herring
2012-07-11 14:44 ` Mark Brown
2012-07-11 20:04 ` Mike Turquette
2012-07-12 4:14 ` Prashant Gaikwad
2012-07-12 14:10 ` Peter De Schrijver
2012-07-12 17:10 ` Mike Turquette
2012-07-12 17:15 ` Mark Brown
2012-07-13 10:34 ` Peter De Schrijver
2012-07-13 17:25 ` Mike Turquette
2012-07-12 4:17 ` Prashant Gaikwad
2012-07-12 15:23 ` Mark Brown
2012-07-12 17:01 ` Mike Turquette
2012-07-12 8:19 ` Peter De Schrijver
2012-07-12 4:08 ` Prashant Gaikwad
2012-07-13 18:30 ` Prashant Gaikwad
2012-07-15 21:40 ` Mark Brown
2012-07-15 23:42 ` Rob Herring
2012-07-16 18:36 ` Turquette, Mike
2012-07-17 12:37 ` Prashant Gaikwad
2012-07-17 13:20 ` Mark Brown
2012-07-17 14:22 ` Prashant Gaikwad
2012-07-17 14:37 ` Mark Brown
2012-07-18 12:46 ` Prashant Gaikwad
2012-07-18 21:19 ` Mark Brown
2012-07-18 17:08 ` Shawn Guo
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