linux-kernel - Re: [PATCH v3 06/12] soc: qcom: geni-se: Introduce helper APIs for performance control

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Message-ID: <24f967b5-0f15-4aed-a81f-ad54f8e541fa@oss.qualcomm.com>
Date: Tue, 3 Feb 2026 12:14:12 +0100
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Praveen Talari <praveen.talari@....qualcomm.com>,
        Andi Shyti <andi.shyti@...nel.org>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley
 <conor+dt@...nel.org>,
        Mukesh Kumar Savaliya <mukesh.savaliya@....qualcomm.com>,
        Viken Dadhaniya <viken.dadhaniya@....qualcomm.com>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>, linux-arm-msm@...r.kernel.org,
        linux-i2c@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, bryan.odonoghue@...aro.org,
        dmitry.baryshkov@....qualcomm.com, bjorn.andersson@....qualcomm.com
Cc: prasad.sodagudi@....qualcomm.com, quic_vtanuku@...cinc.com,
        aniket.randive@....qualcomm.com, chandana.chiluveru@....qualcomm.com
Subject: Re: [PATCH v3 06/12] soc: qcom: geni-se: Introduce helper APIs for
 performance control

On 1/30/26 5:54 PM, Praveen Talari wrote:
> Hi Konrad
> 
> On 1/30/2026 5:53 PM, Konrad Dybcio wrote:
>> On 1/12/26 11:47 AM, Praveen Talari wrote:
>>> The GENI Serial Engine (SE) drivers (I2C, SPI, and SERIAL) currently
>>> manage performance levels and operating points directly. This resulting
>>> in code duplication across drivers. such as configuring a specific level
>>> or find and apply an OPP based on a clock frequency.
>>>
>>> Introduce two new helper APIs, geni_se_set_perf_level() and
>>> geni_se_set_perf_opp(), addresses this issue by providing a streamlined
>>> method for the GENI Serial Engine (SE) drivers to find and set the OPP
>>> based on the desired performance level, thereby eliminating redundancy.
>>>
>>> Signed-off-by: Praveen Talari <praveen.talari@....qualcomm.com>
>>> ---
>>
>> [...]
>>
>>> +/**
>>> + * geni_se_set_perf_level() - Set performance level for GENI SE.
>>> + * @se: Pointer to the struct geni_se instance.
>>> + * @level: The desired performance level.
>>> + *
>>> + * Sets the performance level by directly calling dev_pm_opp_set_level
>>> + * on the performance device associated with the SE.
>>> + *
>>> + * Return: 0 on success, or a negative error code on failure.
>>> + */
>>> +int geni_se_set_perf_level(struct geni_se *se, unsigned long level)
>>> +{
>>> +    return dev_pm_opp_set_level(se->pd_list->pd_devs[DOMAIN_IDX_PERF], level);
>>> +}
>>> +EXPORT_SYMBOL_GPL(geni_se_set_perf_level);
>>
>> This function is never used
> 
> it will be used by UART driver, not for I2C/SPI.

Adding unused exported symbols is "eeeh"..

>>
>>> +
>>> +/**
>>> + * geni_se_set_perf_opp() - Set performance OPP for GENI SE by frequency.
>>> + * @se: Pointer to the struct geni_se instance.
>>> + * @clk_freq: The requested clock frequency.
>>> + *
>>> + * Finds the nearest operating performance point (OPP) for the given
>>> + * clock frequency and applies it to the SE's performance device.
>>> + *
>>> + * Return: 0 on success, or a negative error code on failure.
>>> + */
>>> +int geni_se_set_perf_opp(struct geni_se *se, unsigned long clk_freq)
>>
>> I think with the SPI driver in mind (which seems to do a simple rateset
> 
> APIs were added as generic interfaces shared across I²C/SPI which is specific to firmware control, not Linux control.
> 
>> for both backends) we could do:
>>
>>> +{
>>> +    struct device *perf_dev = se->pd_list->pd_devs[DOMAIN_IDX_PERF];
>>
>> Then, we can do struct device * perf_dev = se->dev;
> I don't think, it is needed since this is specific to firmware control, not Linux control.

My point is that it doesn't have to be specific to the auto usecase,
further commonizing the code..

Konrad