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SubjectRe: [PATCH 2/2] perf: arm_dsu: Support DSU ACPI devices.
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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.

> 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 ?


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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