On 4/15/21 8:59 AM, Matthew Auld wrote:
> Add a note about the two-step process.
>
> Suggested-by: Daniel Vetter <daniel@xxxxxxxx>
> Signed-off-by: Matthew Auld <matthew.auld@xxxxxxxxx>
> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
> Cc: Jordan Justen <jordan.l.justen@xxxxxxxxx>
> Cc: Daniel Vetter <daniel.vetter@xxxxxxxxx>
> Cc: Kenneth Graunke <kenneth@xxxxxxxxxxxxx>
> Cc: Jason Ekstrand <jason@xxxxxxxxxxxxxx>
> Cc: Dave Airlie <airlied@xxxxxxxxx>
> Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> Cc: mesa-dev@xxxxxxxxxxxxxxxxxxxxx
> ---
> include/uapi/drm/i915_drm.h | 57 ++++++++++++++++++++++++++++++-------
> 1 file changed, 46 insertions(+), 11 deletions(-)
>
> diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
> index d9c954a5a456..ef36f1a0adde 100644
> --- a/include/uapi/drm/i915_drm.h
> +++ b/include/uapi/drm/i915_drm.h
> @@ -2210,14 +2210,23 @@ struct drm_i915_perf_oa_config {
> __u64 flex_regs_ptr;
> };
>
> +/**
> + * struct drm_i915_query_item - An individual query for the kernel to process.
> + *
> + * The behaviour is determined by the @query_id. Note that exactly what
Since we just had a big discussion about this on mesa-dev w.r.t. Mesa
code and documentation... does the kernel have a policy about which
flavor (pun intended) of English should be used?
> + * @data_ptr is also depends on the specific @query_id.
> + */
> struct drm_i915_query_item {
> + /** @query_id: The id for this query */
> __u64 query_id;
> #define DRM_I915_QUERY_TOPOLOGY_INFO 1
> #define DRM_I915_QUERY_ENGINE_INFO 2
> #define DRM_I915_QUERY_PERF_CONFIG 3
> /* Must be kept compact -- no holes and well documented */
>
> - /*
> + /**
> + * @length:
> + *
> * When set to zero by userspace, this is filled with the size of the
> * data to be written at the data_ptr pointer. The kernel sets this
> * value to a negative value to signal an error on a particular query
> @@ -2225,21 +2234,26 @@ struct drm_i915_query_item {
> */
> __s32 length;
>
> - /*
> + /**
> + * @flags:
> + *
> * When query_id == DRM_I915_QUERY_TOPOLOGY_INFO, must be 0.
> *
> * When query_id == DRM_I915_QUERY_PERF_CONFIG, must be one of the
> - * following :
> - * - DRM_I915_QUERY_PERF_CONFIG_LIST
> - * - DRM_I915_QUERY_PERF_CONFIG_DATA_FOR_UUID
> - * - DRM_I915_QUERY_PERF_CONFIG_FOR_UUID
> + * following:
> + *
> + * - DRM_I915_QUERY_PERF_CONFIG_LIST
> + * - DRM_I915_QUERY_PERF_CONFIG_DATA_FOR_UUID
> + * - DRM_I915_QUERY_PERF_CONFIG_FOR_UUID
> */
> __u32 flags;
> #define DRM_I915_QUERY_PERF_CONFIG_LIST 1
> #define DRM_I915_QUERY_PERF_CONFIG_DATA_FOR_UUID 2
> #define DRM_I915_QUERY_PERF_CONFIG_DATA_FOR_ID 3
>
> - /*
> + /**
> + * @data_ptr:
> + *
> * Data will be written at the location pointed by data_ptr when the
> * value of length matches the length of the data to be written by the
> * kernel.
> @@ -2247,16 +2261,37 @@ struct drm_i915_query_item {
> __u64 data_ptr;
> };
>
> +/**
> + * struct drm_i915_query - Supply an array of drm_i915_query_item for the kernel
> + * to fill out.
> + *
> + * Note that this is generally a two step process for each drm_i915_query_item
> + * in the array:
> + *
> + * 1.) Call the DRM_IOCTL_I915_QUERY, giving it our array of
> + * drm_i915_query_item, with drm_i915_query_item.size set to zero. The
> + * kernel will then fill in the size, in bytes, which tells userspace how
> + * memory it needs to allocate for the blob(say for an array of
> + * properties).
> + *
> + * 2.) Next we call DRM_IOCTL_I915_QUERY again, this time with the
> + * drm_i915_query_item.data_ptr equal to our newly allocated blob. Note
> + * that the i915_query_item.size should still be the same as what the
> + * kernel previously set. At this point the kernel can fill in the blob.
> + *
> + */
> struct drm_i915_query {
> + /** @num_items: The number of elements in the @items_ptr array */
> __u32 num_items;
>
> - /*
> - * Unused for now. Must be cleared to zero.
> + /**
> + * @flags: Unused for now. Must be cleared to zero.
> */
> __u32 flags;
>
> - /*
> - * This points to an array of num_items drm_i915_query_item structures.
> + /**
> + * @items_ptr: This points to an array of num_items drm_i915_query_item
> + * structures.
> */
> __u64 items_ptr;
> };
>
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