Re: [PATCH v3 3/4] drm/i915/uapi: convert i915_query and friend to kernel doc

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 




On 15/04/2021 16:59, 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
+ * @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.

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.
  	 */
  	__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;
  };

_______________________________________________
Intel-gfx mailing list
Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/intel-gfx



[Index of Archives]     [AMD Graphics]     [Linux USB Devel]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux