linux-kernel - Re: [PATCH v3 1/1] cpufreq: qcom-nvmem: add compatible fallback for ipq806x for no SMEM

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Message-ID: <cb1ced66-8190-4462-99cf-72ec51da6536@oss.qualcomm.com>
Date: Wed, 5 Nov 2025 10:12:08 +0100
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Krzysztof Kozlowski <krzk@...nel.org>,
        Christian Marangi <ansuelsmth@...il.com>,
        Ilia Lin <ilia.lin@...nel.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Viresh Kumar <viresh.kumar@...aro.org>, linux-pm@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Subject: Re: [PATCH v3 1/1] cpufreq: qcom-nvmem: add compatible fallback for
 ipq806x for no SMEM

On 11/5/25 9:05 AM, Krzysztof Kozlowski wrote:
> On 04/11/2025 15:06, Christian Marangi wrote:
>> On some IPQ806x SoC SMEM might be not initialized by SBL. This is the
>> case for some Google devices (the OnHub family) that can't make use of
>> SMEM to detect the SoC ID.
>>
>> To handle these specific case, check if the SMEM is not initialized (by
>> checking if the qcom_smem_get_soc_id returns -ENODEV) and fallback to
>> OF machine compatible checking to identify the SoC variant.
>>
>> Suggested-by: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
>> Signed-off-by: Christian Marangi <ansuelsmth@...il.com>
>> ---
>>  drivers/cpufreq/qcom-cpufreq-nvmem.c | 35 ++++++++++++++++++++++++++--
>>  1 file changed, 33 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/cpufreq/qcom-cpufreq-nvmem.c b/drivers/cpufreq/qcom-cpufreq-nvmem.c
>> index 3a8ed723a23e..17c79955ff2f 100644
>> --- a/drivers/cpufreq/qcom-cpufreq-nvmem.c
>> +++ b/drivers/cpufreq/qcom-cpufreq-nvmem.c
>> @@ -252,13 +252,22 @@ static int qcom_cpufreq_krait_name_version(struct device *cpu_dev,
>>  	return ret;
>>  }
>>  
>> +static const struct of_device_id qcom_cpufreq_ipq806x_match_list[] = {
>> +	{ .compatible = "qcom,ipq8062", .data = (const void *)QCOM_ID_IPQ8062 },
>> +	{ .compatible = "qcom,ipq8064", .data = (const void *)QCOM_ID_IPQ8064 },
>> +	{ .compatible = "qcom,ipq8065", .data = (const void *)QCOM_ID_IPQ8065 },
>> +	{ .compatible = "qcom,ipq8066", .data = (const void *)QCOM_ID_IPQ8066 },
>> +	{ .compatible = "qcom,ipq8068", .data = (const void *)QCOM_ID_IPQ8068 },
>> +	{ .compatible = "qcom,ipq8069", .data = (const void *)QCOM_ID_IPQ8069 },
>> +};
>> +
>>  static int qcom_cpufreq_ipq8064_name_version(struct device *cpu_dev,
>>  					     struct nvmem_cell *speedbin_nvmem,
>>  					     char **pvs_name,
>>  					     struct qcom_cpufreq_drv *drv)
>>  {
>> +	int msm_id = -1, ret = 0;
>>  	int speed = 0, pvs = 0;
>> -	int msm_id, ret = 0;
>>  	u8 *speedbin;
>>  	size_t len;
>>  
>> @@ -275,8 +284,30 @@ static int qcom_cpufreq_ipq8064_name_version(struct device *cpu_dev,
>>  	get_krait_bin_format_a(cpu_dev, &speed, &pvs, speedbin);
>>  
>>  	ret = qcom_smem_get_soc_id(&msm_id);
>> -	if (ret)
>> +	if (ret == -ENODEV) {
>> +		const struct of_device_id *match;
>> +		struct device_node *root;
>> +
>> +		root = of_find_node_by_path("/");
>> +		if (!root) {
>> +			ret = -ENODEV;
>> +			goto exit;
>> +		}
>> +
>> +		/* Fallback to compatible match with no SMEM initialized */
>> +		match = of_match_node(qcom_cpufreq_ipq806x_match_list, root);
> 
> Aren't you re-implementing matching machine? Or actually - the socinfo
> driver? You are doing the matching of compatible into SOC ID second
> time. Just do it once - via socinfo driver.

The issue here is that if SMEM is absent, the socinfo driver can
not function and this is a contained workaround

Konrad