[Intel-gfx] [PATCH 5/5] drm/i915/pmu: Support multiple GPUs

[Chris Wilson]

Quoting Tvrtko Ursulin (2019-08-01 15:17:32)
> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> 
> With discrete graphics system can have both integrated and discrete GPU
> handled by i915.
> 
> Currently we use a fixed name ("i915") when registering as the uncore PMU
> provider which stops working in this case.
> 
> To fix this we add the PCI device name string to non-integrated devices
> handled by us. Integrated devices keep the legacy name preserving
> backward compatibility.
> 
> v2:
>  * Detect IGP and keep legacy name. (Michal)
>  * Use PCI device name as suffix. (Michal, Chris)
> 
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
> ---
> Is our GPU always "0000:00:02.0"? CI will tell me.

It always has been. (With a few additional 2.1 for Windows95 multihead
where each head had to be a unique device!)

One hopes that by now it is firmly ingrained that it will always be
kept to 00:02.0.

> ---
>  drivers/gpu/drm/i915/i915_pmu.c | 27 +++++++++++++++++++++++++--
>  drivers/gpu/drm/i915/i915_pmu.h |  4 ++++
>  2 files changed, 29 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
> index e0e0180bca7c..9a404d85c4e9 100644
> --- a/drivers/gpu/drm/i915/i915_pmu.c
> +++ b/drivers/gpu/drm/i915/i915_pmu.c
> @@ -1053,6 +1053,15 @@ static void i915_pmu_unregister_cpuhp_state(struct i915_pmu *pmu)
>         cpuhp_remove_multi_state(cpuhp_slot);
>  }
>  
> +static bool is_igp(struct pci_dev *pdev)
> +{
> +       /* IGP is 0000:00:02.0 */
> +       return pdev->bus->parent == NULL &&

pci_domain_nr(pdev->bus) == 0 ?

> +              pdev->bus->number == 0 &&
> +              PCI_SLOT(pdev->devfn) == 2 &&
> +              PCI_FUNC(pdev->devfn) == 0;

I am surprised there isn't already a convenience function. None that I
could find.

> +}
> +
>  void i915_pmu_register(struct drm_i915_private *i915)
>  {
>         struct i915_pmu *pmu = &i915->pmu;
> @@ -1083,10 +1092,19 @@ void i915_pmu_register(struct drm_i915_private *i915)
>         hrtimer_init(&pmu->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
>         pmu->timer.function = i915_sample;
>  
> -       ret = perf_pmu_register(&pmu->base, "i915", -1);
> -       if (ret)
> +       if (!is_igp(i915->drm.pdev))
> +               pmu->name = kasprintf(GFP_KERNEL,
> +                                     "i915-%s",
> +                                     dev_name(i915->drm.dev));
> +       else
> +               pmu->name = "i915";

Makes sense, and quite a neat solution.

> +       if (!pmu->name)
>                 goto err;
>  
> +       ret = perf_pmu_register(&pmu->base, pmu->name, -1);
> +       if (ret)
> +               goto err_name;
> +
>         ret = i915_pmu_register_cpuhp_state(pmu);
>         if (ret)
>                 goto err_unreg;
> @@ -1095,6 +1113,9 @@ void i915_pmu_register(struct drm_i915_private *i915)
>  
>  err_unreg:
>         perf_pmu_unregister(&pmu->base);
> +err_name:
> +       if (!is_igp(i915->drm.pdev))
> +               kfree(pmu->name);
kfree_const(pmu->name);

>  err:
>         pmu->base.event_init = NULL;
>         free_event_attributes(pmu);
> @@ -1116,5 +1137,7 @@ void i915_pmu_unregister(struct drm_i915_private *i915)
>  
>         perf_pmu_unregister(&pmu->base);
>         pmu->base.event_init = NULL;
> +       if (!is_igp(i915->drm.pdev))
> +               kfree(pmu->name);

kfree_const(pmu->name);

Works for me, I wonder what PeterZ will say...
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
-Chris