Re: [PATCH 3/6] drm/i915/debugfs: add rcs topology entry

[Lionel Landwerlin <lionel.g.landwerlin@intel.com>]

On 11/01/18 11:31, Tvrtko Ursulin wrote:
>
> 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)
> ...
>
> ?

Yeah, sure.

>
>>     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@chris-wilson.co.uk>
>> Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@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?

Done.

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

Yeah, there are no registers to read on anything < gen8.
I've decided not to generate data there. Most userspaces already has the 
numbers from a table by pci-id.

>
>> +
>> +    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.

Yeah, I'm always using %i, but I must be the only one.
It's been easier to remember int -> %i.

>
>> +               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]) ?

Actually I should use sseu->max_subslices.

>
>> +            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
>

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