linux-kernel - Re: [PATCH v3 2/3] soc: qcom: qcom_stats: Add QMP support for syncing ddr stats

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Message-ID: <bb87014d-cdbb-4dba-8e80-7e9d3a1dd66c@oss.qualcomm.com>
Date: Sun, 25 May 2025 20:29:07 +0530
From: "Maulik Shah (mkshah)" <maulik.shah@....qualcomm.com>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Cc: Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley
 <conor+dt@...nel.org>, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        Doug Anderson <dianders@...omium.org>
Subject: Re: [PATCH v3 2/3] soc: qcom: qcom_stats: Add QMP support for syncing
 ddr stats



On 5/25/2025 6:57 PM, Dmitry Baryshkov wrote:
> On Sun, May 25, 2025 at 02:25:58PM +0530, Maulik Shah wrote:
>> Recent SoCs (SM8450 onwards) require QMP command to be sent before reading
>> ddr stats. The duration field of ddr stats will get populated only if QMP
>> command is sent.
>>
>> Add support to send ddr stats freqsync QMP command.
>>
>> Signed-off-by: Maulik Shah <maulik.shah@....qualcomm.com>
>> ---
>>  drivers/soc/qcom/qcom_stats.c | 34 +++++++++++++++++++++++++++++++++-
>>  1 file changed, 33 insertions(+), 1 deletion(-)
>>
>> @@ -310,6 +329,19 @@ static int qcom_stats_probe(struct platform_device *pdev)
>>  	qcom_create_subsystem_stat_files(root, config);
>>  	qcom_create_soc_sleep_stat_files(root, reg, d, config);
>>  	qcom_create_ddr_stat_files(root, reg, config);
>> +	/*
>> +	 * QMP is used for DDR stats syncing to MSG RAM for recent SoCs (SM8450 onwards).
>> +	 * The prior SoCs do not need QMP handle as the required stats are already present
>> +	 * in MSG RAM, provided the DDR_STATS_MAGIC_KEY matches.
>> +	 */
>> +	qcom_stats_qmp = qmp_get(&pdev->dev);
>> +	if (IS_ERR(qcom_stats_qmp)) {
>> +		if (PTR_ERR(qcom_stats_qmp) == -EPROBE_DEFER)
>> +			return -EPROBE_DEFER;
>> +
>> +		/* We assume any other error means it's not defined/needed */
>> +		qcom_stats_qmp = NULL;
> 
> If you return here, who will cleanup your actions? At least you've
> registered debugfs files...

I will keep this part ahead in probe in v4 before creating debugfs files to make sure
no clean up in driver is needed in case of probe defer.

Thanks,
Maulik

> 
>> +	}
>>  
>>  	platform_set_drvdata(pdev, root);
>>  
>>
>> -- 
>> 2.34.1
>>
>