From: Lukasz Luba <lukasz.luba@arm.com>
To: Doug Anderson <dianders@chromium.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Linux PM <linux-pm@vger.kernel.org>,
linux-doc@vger.kernel.org,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>, Rob Herring <robh+dt@kernel.org>,
amitk@kernel.org, Jonathan Corbet <corbet@lwn.net>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
Dietmar.Eggemann@arm.com, Quentin Perret <qperret@google.com>,
Matthias Kaehlcke <mka@chromium.org>,
Rajendra Nayak <rnayak@codeaurora.org>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>
Subject: Re: [PATCH v2 3/3] dt-bindings: thermal: update sustainable-power with abstract scale
Date: Fri, 2 Oct 2020 16:12:55 +0100 [thread overview]
Message-ID: <e9b6fc5a-45d3-168d-db38-6c068da26f6b@arm.com> (raw)
In-Reply-To: <CAD=FV=UbNP5-G1z95F37Fmv8=n0JPSSwnPQO_K==WpAc4vAHWQ@mail.gmail.com>
Hi Doug,
On 10/2/20 3:31 PM, Doug Anderson wrote:
> Hi,
>
> On Fri, Oct 2, 2020 at 4:45 AM Lukasz Luba <lukasz.luba@arm.com> wrote:
>>
>> Update the documentation for the binding 'sustainable-power' and allow
>> to provide values in an abstract scale. It is required when the cooling
>> devices use an abstract scale for their power values.
>>
>> Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
>> ---
>> .../devicetree/bindings/thermal/thermal-zones.yaml | 13 +++++++++----
>> 1 file changed, 9 insertions(+), 4 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/thermal/thermal-zones.yaml b/Documentation/devicetree/bindings/thermal/thermal-zones.yaml
>> index 3ec9cc87ec50..4d8f2e37d1e6 100644
>> --- a/Documentation/devicetree/bindings/thermal/thermal-zones.yaml
>> +++ b/Documentation/devicetree/bindings/thermal/thermal-zones.yaml
>> @@ -99,10 +99,15 @@ patternProperties:
>> sustainable-power:
>> $ref: /schemas/types.yaml#/definitions/uint32
>> description:
>> - An estimate of the sustainable power (in mW) that this thermal zone
>> - can dissipate at the desired control temperature. For reference, the
>> - sustainable power of a 4-inch phone is typically 2000mW, while on a
>> - 10-inch tablet is around 4500mW.
>> + An estimate of the sustainable power (in mW or in an abstract scale)
>> + that this thermal zone can dissipate at the desired control
>> + temperature. For reference, the sustainable power of a 4-inch phone
>> + is typically 2000mW, while on a 10-inch tablet is around 4500mW.
>> +
>> + It is possible to express the sustainable power in an abstract
>> + scale. This is the case when the related cooling devices use also
>> + abstract scale to express their power usage. The scale must be
>> + consistent.
>
> Two thoughts:
>
> 1. If we're going to allow "sustainable-power" to be in abstract
> scale, why not allow "dynamic-power-coefficient" to be in abstract
> scale too? I assume that the whole reason against that originally was
> the idea of device tree purity, but if we're allowing the abstract
> scale here then there seems no reason not to allow it for
> "dynamic-power-coefficient".
With this binding it's a bit more tricky.
I also have to discuss a few things internally. This requirement of
uW/MHz/V^2 makes the code easier also for potential drivers
like GPU (which are going to register the devfreq cooling with EM).
Let me think about it, but for now I would just update these bits.
These are required to proper IPA operation, the dyn.-pow.-coef. is a
nice to have and possible next step.
>
> 2. Is it worth adding some type of indication of what type of units
> "sustainable-power" is represented in? Maybe even a made up unit so
> that you could tell the difference between made up units in the same
> system? I'd envision something like:
>
> sustainable-power-units = "qualcomm,sc7180-bogoWatts"
>
> ...and on the dynamic-power-coefficient side, the same:
>
> dynamic-power-coefficient-units = "qualcomm,sc7180-bogoWatts"
>
> One could imagine someone even later (after devices are widely
> distributed) figuring out translations between these bogoWatts numbers
> and real Watts if someone could come up with a case where it matters.
To figure this out we don't need a new binding.
I think a simple comment in the DT would be enough for this, even e.g.:
sustainable-power = <100> /* bogoWatts */
Thank you for your comments.
BTW, I haven't put your 'Reviewed-by' because I have added this
sustainable-power new stuff in patch 1/3. I will grateful if you
have a look on that.
Regards,
Lukasz
next prev parent reply other threads:[~2020-10-02 15:13 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-02 11:44 [PATCH v2 0/3] Clarify abstract scale usage for power values in Energy Model, EAS and IPA Lukasz Luba
2020-10-02 11:44 ` [PATCH v2 1/3] docs: Clarify abstract scale usage for power values in Energy Model Lukasz Luba
2020-10-02 11:44 ` [PATCH v2 2/3] PM / EM: update the comments related to power scale Lukasz Luba
2020-10-02 11:44 ` [PATCH v2 3/3] dt-bindings: thermal: update sustainable-power with abstract scale Lukasz Luba
2020-10-02 14:31 ` Doug Anderson
2020-10-02 15:12 ` Lukasz Luba [this message]
2020-10-02 15:47 ` Doug Anderson
2020-10-02 16:40 ` Lukasz Luba
2020-10-02 17:39 ` Doug Anderson
2020-10-06 22:24 ` Rob Herring
2020-10-07 1:17 ` Doug Anderson
2020-10-07 13:26 ` Rob Herring
2020-10-07 21:40 ` Doug Anderson
2020-10-08 14:20 ` Lukasz Luba
2020-10-08 16:41 ` Doug Anderson
2020-10-07 9:03 ` Lukasz Luba
2020-10-05 13:58 ` Rob Herring
2020-10-05 16:14 ` Lukasz Luba
2020-10-09 9:16 ` [PATCH v2 0/3] Clarify abstract scale usage for power values in Energy Model, EAS and IPA Lukasz Luba
2020-10-14 8:22 ` Daniel Lezcano
2020-10-14 9:08 ` Lukasz Luba
2020-10-14 11:23 ` Daniel Lezcano
2020-10-14 15:24 ` Lukasz Luba
2020-10-14 17:10 ` Daniel Lezcano
2020-10-15 9:00 ` Lukasz Luba
2020-10-15 10:21 ` Daniel Lezcano
2020-10-15 13:40 ` Rafael J. Wysocki
2020-10-15 15:04 ` Quentin Perret
2020-10-16 11:48 ` Daniel Lezcano
2020-10-16 12:18 ` Quentin Perret
2020-10-16 12:50 ` Daniel Lezcano
2020-10-16 13:09 ` Quentin Perret
2020-10-16 14:36 ` Doug Anderson
2020-10-16 15:55 ` Quentin Perret
2020-10-16 14:42 ` Lukasz Luba
2020-10-16 16:02 ` Quentin Perret
2020-10-19 10:35 ` Lukasz Luba
2020-10-15 13:33 ` Rafael J. Wysocki
2020-10-15 13:39 ` Daniel Lezcano
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