[Intel-gfx] [PATCH 3/6] drm/i915/debugfs: add rcs topology entry

[Tvrtko Ursulin]

On 18/12/2017 15:35, Lionel Landwerlin wrote:
> While the end goal is to make this information available to userspace
> through a new ioctl, there is no reason we can't display it in a human
> readable fashion through debugfs.
> 
> slice0 (subslice_mask=0x7):

I'd add a subslice count while at it, since the eu lines have counts.

Bike-shedding on whether counts or masks are typically more important?

Slice0: 3 slices (0x7):
	Subslice 0: 8 EUs (0xff)
	Subslice 1: 8 EUs (0xff)
...

?

> 	subslice0:
> 		eu_mask: 0xff (8)
> 	subslice1:
> 		eu_mask: 0xff (8)
> 	subslice2:
> 		eu_mask: 0xff (8)
> 	subslice3:
> 		eu_mask: 0x0 (0)
> slice1 (subslice_mask=0x7):
> 	subslice0:
> 		eu_mask: 0xff (8)
> 	subslice1:
> 		eu_mask: 0xff (8)
> 	subslice2:
> 		eu_mask: 0xff (8)
> 	subslice3:
> 		eu_mask: 0x0 (0)
> slice2 (subslice_mask=0x7):
> 	subslice0:
> 		eu_mask: 0xff (8)
> 	subslice1:
> 		eu_mask: 0xff (8)
> 	subslice2:
> 		eu_mask: 0xff (8)
> 	subslice3:
> 		eu_mask: 0x0 (0)
> 
> Suggested-by: Chris Wilson <chris at chris-wilson.co.uk>
> Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
> ---
>   drivers/gpu/drm/i915/i915_debugfs.c | 37 +++++++++++++++++++++++++++++++++++++
>   1 file changed, 37 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index 6ec7543e698f..79ca6e9f9ec9 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -3173,6 +3173,42 @@ static int i915_engine_info(struct seq_file *m, void *unused)
>   	return 0;
>   }
>   
> +static int i915_rcs_topology(struct seq_file *m, void *unused)
> +{
> +	struct drm_i915_private *dev_priv = node_to_i915(m->private);
> +	const struct sseu_dev_info *sseu = &INTEL_INFO(dev_priv)->sseu;
> +	int s, ss;
> +	int subslice_stride = ALIGN(sseu->max_eus_per_subslice, 8) / 8;
> +	int slice_stride = sseu->max_subslices * subslice_stride;

Another case for the before mentioned helper for indexing into eu_mask 
array?

> +
> +	if (sseu->max_slices == 0) {
> +		seq_printf(m, "Unavailable\n");
> +		return 0;
> +	}

Is this possible?

> +
> +	for (s = 0; s < sseu->max_slices; s++) {
> +		seq_printf(m, "slice%i (subslice_mask=0x%x):\n",

%i always confuses me. Googling shows it is equivalent to %d for 
printing? Or is it something different in kernel space? If it is 
equivalent I would go with a more standard one. And I would even change 
to unsigned variables for iterators but I realize some people have a 
different opinion so up to you.

> +			   s, sseu->subslices_mask[s]);
> +
> +		for (ss = 0; ss < slice_stride / subslice_stride; ss++) {

With the indexing helpers hopefully it would be possible to simply 
iterate to hweight8(sseu->sublice_mask[s]) ?

> +			int eu, n_subslice_eus = 0;
> +
> +			seq_printf(m, "\tsubslice%i:\n", ss);
> +
> +			seq_printf(m, "\t\teu_mask:");
> +			for (eu = 0; eu < subslice_stride; eu++) {
> +				u8 val = sseu->eu_mask[s * slice_stride +
> +						       ss * subslice_stride + eu];
> +				seq_printf(m, " 0x%x", val);
> +				n_subslice_eus += hweight8(val);
> +			}
> +			seq_printf(m, " (%i)\n", n_subslice_eus);
> +		}
> +	}
> +
> +	return 0;
> +}
> +
>   static int i915_shrinker_info(struct seq_file *m, void *unused)
>   {
>   	struct drm_i915_private *i915 = node_to_i915(m->private);
> @@ -4658,6 +4694,7 @@ static const struct drm_info_list i915_debugfs_list[] = {
>   	{"i915_dmc_info", i915_dmc_info, 0},
>   	{"i915_display_info", i915_display_info, 0},
>   	{"i915_engine_info", i915_engine_info, 0},
> +	{"i915_rcs_topology", i915_rcs_topology, 0},
>   	{"i915_shrinker_info", i915_shrinker_info, 0},
>   	{"i915_shared_dplls_info", i915_shared_dplls_info, 0},
>   	{"i915_dp_mst_info", i915_dp_mst_info, 0},
> 

Regards,

Tvrtko