On 15/04/2021 16:59, Matthew Auld wrote:
Add a note about the two-step process.
Suggested-by: Daniel Vetter daniel@ffwll.ch Signed-off-by: Matthew Auld matthew.auld@intel.com Cc: Joonas Lahtinen joonas.lahtinen@linux.intel.com Cc: Jordan Justen jordan.l.justen@intel.com Cc: Daniel Vetter daniel.vetter@intel.com Cc: Kenneth Graunke kenneth@whitecape.org Cc: Jason Ekstrand jason@jlekstrand.net Cc: Dave Airlie airlied@gmail.com Cc: dri-devel@lists.freedesktop.org Cc: mesa-dev@lists.freedesktop.org
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
- @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
- /*
- /**
* @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.
I'd also document the one step alternative where userspace passes in a buffer equal or larger than the required size. For many small queries (most?) this actually works just as well and with one ioctl only.
Regards,
Tvrtko
- */ 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.
- /*
* 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.