[Intel-gfx] [PATCH v9 6/6] drm/i915: expose rcs topology through query uAPI

[Lionel Landwerlin]

On 18/01/18 15:18, Chris Wilson wrote:
> Quoting Lionel Landwerlin (2018-01-18 14:45:31)
>> +static int query_slice_info(struct drm_i915_private *dev_priv,
>> +                           struct drm_i915_query_item *query_item)
>> +{
>> +       const struct sseu_dev_info *sseu = &INTEL_INFO(dev_priv)->sseu;
>> +       struct drm_i915_query_slice_info slice_info;
>> +
>> +       if (query_item->flags != 0)
>> +               return -EINVAL;
>> +
>> +       if (sseu->max_slices == 0)
>> +               return -ENODEV;
> So conclusion was to cancel all queries and not report a 0-length result
> for unsupported? :)
> -Chris
>
Looking at GETPARAM, some queries return ENODEV if not supported (look 
at SLICE_MASK, so did the same here).
Error are now reported in the s32 length field of the query item.
Unless you've screwed up the pointer to the items, in which case you'll 
get an error through the ioctl() return value.

Does that sounds sensible?