[Intel-gfx] [PATCH] drm/i915/debugfs: Dump i915 children runtime status

[Dixit, Ashutosh]

On Mon, 28 Mar 2022 03:22:27 -0700, Anshuman Gupta wrote:
>
> +#ifdef CONFIG_PM
> +static int i915_runtime_dump_child_status(struct device *dev, void *data)
> +{
> +	struct seq_file *m = data;
> +	const char *rpm_status;
> +
> +	/* Early return if runtime_pm is disabled */
> +	if (dev->power.disable_depth)
> +		return 0;
> +
> +	switch (dev->power.runtime_status) {
> +	case RPM_SUSPENDED:
> +		rpm_status = "suspended";
> +		break;
> +	case RPM_SUSPENDING:
> +		rpm_status = "suspending";
> +		break;
> +	case RPM_RESUMING:
> +		rpm_status = "resuming";
> +		break;
> +	case RPM_ACTIVE:
> +		rpm_status = "active";
> +		break;
> +	default:
> +		rpm_status = "unknown";
> +	}
> +
> +	seq_printf(m, "\t%s %s: Runtime status: %s\n", dev_driver_string(dev),
> +		   dev_name(dev), rpm_status);
> +
> +	return 0;
> +}
> +#endif

Maybe a nit, but perhaps defining a const array is better than having a
switch statement? Similar to what is done in rtpm_status_str(). The
function itself is very similar to rtpm_status_str() so can probably
benefit from that similarity. Can perhaps even be nearly identical to
rtpm_status_str() (since that is static in the genpd (generic power domain)
code).

See also 2bd5306a8764 ("PM / Domains: add debugfs listing of struct
generic_pm_domain-s"), though I am not sure if genpd's are applicable in
our case and certainly look way out of scope for now. Thanks.

> +
>  static int i915_runtime_pm_status(struct seq_file *m, void *unused)
>  {
>	struct drm_i915_private *dev_priv = node_to_i915(m->private);
> @@ -500,6 +534,10 @@ static int i915_runtime_pm_status(struct seq_file *m, void *unused)
>  #ifdef CONFIG_PM
>	seq_printf(m, "Usage count: %d\n",
>		   atomic_read(&dev_priv->drm.dev->power.usage_count));
> +	seq_printf(m, "Runtime active children: %d\n",
> +		   atomic_read(&dev_priv->drm.dev->power.child_count));
> +	device_for_each_child(&pdev->dev, m, i915_runtime_dump_child_status);
> +
>  #else
>	seq_printf(m, "Device Power Management (CONFIG_PM) disabled\n");
>  #endif
> --
> 2.26.2
>