Hi,
On 11/29/2016 04:52 AM, Will Deacon wrote:
On Wed, Nov 09, 2016 at 05:39:51PM -0600, Jeremy Linton wrote:
On systems with multiple PMU types the PMU to CPU affinity
needs to be detected and set. The CPU to interrupt affinity
should also be set.
(trimming)
+static int probe_plat_pmu(struct arm_pmu *pmu,
+ const struct pmu_probe_info *info,
+ unsigned int pmuid)
{
- int cpu = get_cpu();
- unsigned int cpuid = read_cpuid_id();
int ret = -ENODEV;
+ int cpu;
+ int aff_ctr = 0;
+ static int duplicate_pmus;
+ struct platform_device *pdev = pmu->plat_device;
+ int irq = platform_get_irq(pdev, 0);
- pr_info("probing PMU on CPU %d\n", cpu);
+ if (irq >= 0 && !irq_is_percpu(irq)) {
+ pmu->irq_affinity = kcalloc(pdev->num_resources, sizeof(int),
+ GFP_KERNEL);
+ if (!pmu->irq_affinity)
+ return -ENOMEM;
+ }
+ for_each_possible_cpu(cpu) {
+ unsigned int cpuid = read_specific_cpuid(cpu);
+
+ if (cpuid == pmuid) {
+ cpumask_set_cpu(cpu, &pmu->supported_cpus);
+ if (pmu->irq_affinity) {
+ pmu->irq_affinity[aff_ctr] = cpu;
+ aff_ctr++;
+ }
+ }
+ }
+
+ /* find the type of PMU given the CPU */
for (; info->init != NULL; info++) {
- if ((cpuid & info->mask) != info->cpuid)
+ if ((pmuid & info->mask) != info->cpuid)
continue;
ret = info->init(pmu);
+ /*
+ * if this pmu declaration is unspecified and we have
+ * previously found a PMU on this platform then append
+ * a PMU number to the pmu name. This avoids changing
+ * the names of PMUs that are specific to a class of CPUs.
+ * The assumption is that if we match a specific PMU in the
+ * provided pmu_probe_info then it's unique, and another PMU
+ * in the system will match a different entry rather than
+ * needing the _number to assure its unique.
+ */
+ if ((!info->cpuid) && (duplicate_pmus)) {
This is a bit grim: if you had a PMU with a non-zero info->cpuid, then you
later found a PMU with a zeroed info->cpuid, the latter would get a
redundant suffix. This doesn't happen in reality, because the ACPI case
always has info->cpuid == 0, but if somebody extends armv8_pmu_probe_table
then we'd get this and probably not realise.
Hoisting the duplicate_pmus inside the !info->cpuid fixes that...
I think the duplicate_pmus counter needs to be tied explicitly to the
"default type" (i.e. when info->cpuid == 0, but see my next comment).
+ pmu->name = kasprintf(GFP_KERNEL, "%s_%d",
+ pmu->name, duplicate_pmus);
+ if (!pmu->name) {
+ kfree(pmu->irq_affinity);
+ ret = -ENOMEM;
+ }
+ }
This code doesn't run for the device-tree probing case, but I think it would
be useful to do the same numbering trick for e.g. systems with multiple PMUs
that all end up matching on armv8_pmuv3.
Ok, its pretty straightforward to move the check into
arm_pmu_device_probe() itself and do a string compare against
DEFAULT_V8_PMU define rather than !cpuid.
Ok, I will do that and post v11 as soon as I hear from Russell about
what he wants to do with read_specific_cpuid().
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