Reviewed-by: Jason Ekstrand <jason@xxxxxxxxxxxxxx>
On April 16, 2021 05:37:55 Matthew Auld <matthew.auld@xxxxxxxxx> wrote:
Add a note about the two-step process.v2(Tvrtko):- Also document the other method of just passing in a buffer which islarge enough, which avoids two ioctl calls. Can make sense forsmaller query items.Suggested-by: Daniel Vetter <daniel@xxxxxxxx>Signed-off-by: Matthew Auld <matthew.auld@xxxxxxxxx>Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>Cc: Tvrtko Ursulin <tvrtko.ursulin@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@xxxxxxxxxxxxxxxxxxxxxCc: mesa-dev@xxxxxxxxxxxxxxxxxxxxxReviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>---include/uapi/drm/i915_drm.h | 61 ++++++++++++++++++++++++++++++-------1 file changed, 50 insertions(+), 11 deletions(-)diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.hindex d79b51c12ff2..12f375c52317 100644--- a/include/uapi/drm/i915_drm.h+++ b/include/uapi/drm/i915_drm.h@@ -2218,14 +2218,23 @@ 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@@ -2233,21 +2242,26 @@ 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.@@ -2255,16 +2269,41 @@ 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.+ *+ * Note that for some query items it can make sense for userspace to just pass+ * in a buffer/blob equal to or larger than the required size. In this case only+ * a single ioctl call is needed. For some smaller query items this can work+ * quite well.+ *+ */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;};--2.26.3
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