Re: [PATCH v2 09/26] cpufreq: qcom-nvmem: create L2 cache device

[Dmitry Baryshkov <dmitry.baryshkov@linaro.org>]

On 26/06/2023 14:50, Konrad Dybcio wrote:
> On 25.06.2023 22:25, Dmitry Baryshkov wrote:
>> Scaling the frequencies on some of Qualcomm Krait platforms (e.g.
>> APQ8064) also requires scaling of the L2 cache frequency. As the
>> l2-cache device node is places under /cpus/ path, it is not created by
>> default by the OF code. Create corresponding device here.
>>
>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
>> ---
> I think a generic solution (i.e. for each cpu node call
> of_platform_populate in drivers/of/platform.c :
> of_platform_default_populate_init) could be beneficial

Yep. I thought about it, but I saw no direct benefit for it. Note, that 
we do not instantiate cpu devices directly. But, maybe something like 
/devices/system/cache/foo would make sense.

> 
> Konrad
>>   drivers/cpufreq/qcom-cpufreq-nvmem.c | 20 ++++++++++++++++++++
>>   1 file changed, 20 insertions(+)
>>
>> diff --git a/drivers/cpufreq/qcom-cpufreq-nvmem.c b/drivers/cpufreq/qcom-cpufreq-nvmem.c
>> index a88b6fe5db50..ab78ef1531d0 100644
>> --- a/drivers/cpufreq/qcom-cpufreq-nvmem.c
>> +++ b/drivers/cpufreq/qcom-cpufreq-nvmem.c
>> @@ -380,6 +380,7 @@ static int __init qcom_cpufreq_init(void)
>>   {
>>   	struct device_node *np = of_find_node_by_path("/");
>>   	const struct of_device_id *match;
>> +	unsigned int cpu;
>>   	int ret;
>>   
>>   	if (!np)
>> @@ -390,6 +391,25 @@ static int __init qcom_cpufreq_init(void)
>>   	if (!match)
>>   		return -ENODEV;
>>   
>> +	for_each_possible_cpu(cpu) {
>> +		struct device *dev = get_cpu_device(cpu);
>> +		struct device_node *cache;
>> +		struct platform_device *pdev;
>> +
>> +		cache = of_find_next_cache_node(dev->of_node);
>> +		if (!cache)
>> +			continue;
>> +
>> +		if (of_device_is_compatible(cache, "qcom,krait-l2-cache")) {
>> +			pdev = of_platform_device_create(cache, NULL, NULL);
>> +			if (IS_ERR(pdev))
>> +				pr_err("%s: %pe, failed to create L2 cache node\n", __func__, pdev);
>> +			/* the error is not fatal */
>> +		}
>> +
>> +		of_node_put(cache);
>> +	}
>> +
>>   	ret = platform_driver_register(&qcom_cpufreq_driver);
>>   	if (unlikely(ret < 0))
>>   		return ret;

-- 
With best wishes
Dmitry