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SubjectRe: [PATCH 2/2] perf: arm_dsu: Support DSU ACPI devices.
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Thanks Suzuki and Robin for quick reply.
Please find my comments below.

> On Mar 18, 2020, at 5:45 PM, Suzuki K Poulose <suzuki.poulose@arm.com> wrote:
>
> Hello,
>
>
> Please find my comments below.
>
> On 03/18/2020 12:28 AM, Tuan Phan wrote:
>> Add support for probing device from ACPI node.
>> Each DSU ACPI node defines "cpus" package which
>> each element is the MPIDR of associated cpu.
>> Signed-off-by: Tuan Phan <tuanphan@os.amperecomputing.com>
>> ---
>> drivers/perf/arm_dsu_pmu.c | 53 +++++++++++++++++++++++++++++++++++++++-------
>> 1 file changed, 45 insertions(+), 8 deletions(-)
>> diff --git a/drivers/perf/arm_dsu_pmu.c b/drivers/perf/arm_dsu_pmu.c Tua
>> index 2622900..6ef762c 100644
>> --- a/drivers/perf/arm_dsu_pmu.c
>> +++ b/drivers/perf/arm_dsu_pmu.c
>> @@ -11,6 +11,7 @@
>> #define DRVNAME PMUNAME "_pmu"
>> #define pr_fmt(fmt) DRVNAME ": " fmt
>> +#include <linux/acpi.h>
>> #include <linux/bitmap.h>
>> #include <linux/bitops.h>
>> #include <linux/bug.h>
>> @@ -603,18 +604,22 @@ static struct dsu_pmu *dsu_pmu_alloc(struct platform_device *pdev)
>> }
>> /**
>> - * dsu_pmu_dt_get_cpus: Get the list of CPUs in the cluster.
>> + * dsu_pmu_get_cpus: Get the list of CPUs in the cluster.
>> */
>> -static int dsu_pmu_dt_get_cpus(struct device_node *dev, cpumask_t *mask)
>> +static int dsu_pmu_get_cpus(struct platform_device *pdev)
>> {
>> +#ifndef CONFIG_ACPI
>> + /* Get the list of CPUs from device tree */
>
> What if we have a kernel with both:
>
> CONFIG_OF=y
> CONFIG_ACPI=y
>
> and boot the kernel on a system with DT ? In other words, the decision
> to choose the DT vs ACPI must be runtime decision, not buildtime.
>
> See drivers/hwtracing/coresight/coresight-platform.c:coresight_get_platform_data() for an example.

I will update so it can be detected in runtime.

>> int i = 0, n, cpu;
>> struct device_node *cpu_node;
>> + struct dsu_pmu *dsu_pmu =
>> + (struct dsu_pmu *) platform_get_drvdata(pdev);
>> - n = of_count_phandle_with_args(dev, "cpus", NULL);
>> + n = of_count_phandle_with_args(pdev->dev.of_node, "cpus", NULL);
>> if (n <= 0)
>> return -ENODEV;
>> for (; i < n; i++) {
>> - cpu_node = of_parse_phandle(dev, "cpus", i);
>> + cpu_node = of_parse_phandle(pdev->dev.of_node, "cpus", i);
>> if (!cpu_node)
>> break;
>> cpu = of_cpu_node_to_id(cpu_node);
>> @@ -626,9 +631,33 @@ static int dsu_pmu_dt_get_cpus(struct device_node *dev, cpumask_t *mask)
>> */
>> if (cpu < 0)
>> continue;
>> - cpumask_set_cpu(cpu, mask);
>> + cpumask_set_cpu(cpu, &dsu_pmu->associated_cpus);
>> }
>> return 0;
>> +#else /* CONFIG_ACPI */
>> + int i, cpu, ret;
>> + const union acpi_object *obj;
>> + struct acpi_device *adev = ACPI_COMPANION(&pdev->dev);
>> + struct dsu_pmu *dsu_pmu =
>> + (struct dsu_pmu *) platform_get_drvdata(pdev);
>> +
>
>> + ret = acpi_dev_get_property(adev, "cpus", ACPI_TYPE_ANY, &obj);
>
> Is the binding documented somewhere ?

=> Will add one.

>
>
> nit: Also, why not :
> ret = acpi_dev_get_propert(adev, "cpus", ACPI_TYPE_PACKAGE, &obj);
> if (ret < 0)
> return ret;
> ?
>
>
>> + if (ret < 0)
>> + return -EINVAL;
>> +
>> + if (obj->type != ACPI_TYPE_PACKAGE)
>> + return -EINVAL;
>> +
>> + for (i = 0; i < obj->package.count; i++) {
>
>
>> + /* Each element is the MPIDR of associated cpu */
>> + for_each_possible_cpu(cpu) {
>> + if (cpu_physical_id(cpu) ==
>> + obj->package.elements[i].integer.value)
>> + cpumask_set_cpu(cpu, &dsu_pmu->associated_cpus);
>> + }
>> + }
>> + return 0;
>> +#endif
>> }
>>
>
> Otherwise looks good to me.
>
> Suzuki

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