From: Krzysztof Kozlowski <krzk@kernel.org>
To: Imran Shaik <imran.shaik@oss.qualcomm.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>,
Viresh Kumar <viresh.kumar@linaro.org>,
Rob Herring <robh@kernel.org>,
Krzysztof Kozlowski <krzk+dt@kernel.org>,
Conor Dooley <conor+dt@kernel.org>,
Manivannan Sadhasivam <mani@kernel.org>,
Ajit Pandey <ajit.pandey@oss.qualcomm.com>,
Taniya Das <taniya.das@oss.qualcomm.com>,
Jagadeesh Kona <jagadeesh.kona@oss.qualcomm.com>,
linux-pm@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org
Subject: Re: [PATCH 1/2] dt-bindings: cpufreq: qcom-hw: Document Shikra CPUFREQ Hardware
Date: Tue, 5 May 2026 10:53:05 +0200 [thread overview]
Message-ID: <eebae734-3b03-4848-a728-a29d8a210e57@kernel.org> (raw)
In-Reply-To: <8101e2c8-0593-4325-a701-84f776dd4b0a@oss.qualcomm.com>
On 05/05/2026 10:50, Imran Shaik wrote:
>
>
> On 04-05-2026 03:53 pm, Krzysztof Kozlowski wrote:
>> On Fri, May 01, 2026 at 12:45:44PM +0530, Imran Shaik wrote:
>>> The Qualcomm Shikra cpufreq hardware is functionally identical to EPSS,
>>> but supports only up to 12 frequency lookup table (LUT) entries. Introduce
>>> qcom,cpufreq-epss-lite to represent this constrained EPSS variant.
>>
>> The entire point of having a generic compatible is that it MUST match
>> all devices. If it does not, then it is pointless to push that generic
>> compatible.
>>
>> I am speaking about qcom,cpufreq-epss.
>>
>> That's nothing new, I was arguing about it already, but now you have
>> confirmation of the mess introduced by generic compatibles. Solution is
>> not to add more generic compatibles, because what will be next?
>> qcom,cpufreq-epss-lighter?
>> qcom,cpufreq-epss-more-lite?
>> qcom,cpufreq-epss-high?
>>
>> Same was here:
>> https://lore.kernel.org/all/20240828203721.2751904-17-quic_nkela@quicinc.com/
>>
>> So that's second time I object and do object for every new instance. No
>> to generic compatibles, they are proven to be wrong at least for
>> Qualcomm.
>>
>> Best regards,
>> Krzysztof
>>
>
> Hi Krzysztof,
>
> There is no functional change to the latest EPSS hardware
> (qcom,cpufreq-epss) in this case. The Shikra platform uses the CPU
> frequency scaling block, which is a predecessor of EPSS and is referred
> to as EPSS‑lite. The only difference between EPSS‑lite and EPSS is the
> maximum number of frequency look up table (LUT) entries.
>
> This constrained EPSS block is not specific to Shikra and can be reused
> by other SoCs that implement the same hardware. Hence, we have added a
> separate epss-lite compatible and reused the existing bindings, as all
> other aspects of the hardware behavior and interface remain identical.
I don't understand how any of this is relevant to my comment. I know
what you did.
Best regards,
Krzysztof
next prev parent reply other threads:[~2026-05-05 8:53 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-01 7:15 [PATCH 0/2] Add cpufreq scaling support for Qualcomm Shikra SoC Imran Shaik
2026-05-01 7:15 ` [PATCH 1/2] dt-bindings: cpufreq: qcom-hw: Document Shikra CPUFREQ Hardware Imran Shaik
2026-05-04 10:23 ` Krzysztof Kozlowski
2026-05-05 8:50 ` Imran Shaik
2026-05-05 8:53 ` Krzysztof Kozlowski [this message]
2026-05-01 7:15 ` [PATCH 2/2] cpufreq: qcom: Add cpufreq scaling support for Qualcomm Shikra SoC Imran Shaik
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=eebae734-3b03-4848-a728-a29d8a210e57@kernel.org \
--to=krzk@kernel.org \
--cc=ajit.pandey@oss.qualcomm.com \
--cc=conor+dt@kernel.org \
--cc=devicetree@vger.kernel.org \
--cc=imran.shaik@oss.qualcomm.com \
--cc=jagadeesh.kona@oss.qualcomm.com \
--cc=krzk+dt@kernel.org \
--cc=linux-arm-msm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pm@vger.kernel.org \
--cc=mani@kernel.org \
--cc=rafael@kernel.org \
--cc=robh@kernel.org \
--cc=taniya.das@oss.qualcomm.com \
--cc=viresh.kumar@linaro.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox