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

[Nilawar, Badal]

On 28-03-2022 15:52, Anshuman Gupta wrote:
> i915 doesn't use pm_suspend_ignore_children() which warrants that
> any runtime active child of i915 will block the runtime suspend
> of i915.
> i915_runtime_pm_status only exposes i915 runtime pm usage_count,
> which is not sufficient to debug in the scenarios when i915 has
> zero usage_count but there are runtime active children.
> Dump i915 child's runtime pm status to debug such
> i915 runtime suspend issues.
> 
> Cc: Chris Wilson <chris.p.wilson at intel.com>
> Signed-off-by: Anshuman Gupta <anshuman.gupta at intel.com>
> ---
>   drivers/gpu/drm/i915/i915_debugfs.c | 38 +++++++++++++++++++++++++++++
>   1 file changed, 38 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index 445b4da23950..ea1730419f8d 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -483,6 +483,40 @@ static int i915_rps_boost_info(struct seq_file *m, void *data)
>   	return 0;
>   }
>   
> +#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
> +
>   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);
> +
These changes looks fine to me.
Reviewed-by: Badal Nilawar <badal.nilawar at intel.com>
>   #else
>   	seq_printf(m, "Device Power Management (CONFIG_PM) disabled\n");
>   #endif