drm/xe/uapi: Add examples of user space code

Complete the documentation of some structs by adding functional
examples of user space code. Those examples are intentionally kept
very simple. Put together, they provide a foundation for a minimal
application that executes a job using the Xe driver.

v2: Remove use of DRM_XE_VM_BIND_FLAG_ASYNC (Francois Dugast)
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Acked-by: José Roberto de Souza <jose.souza@intel.com>
Acked-by: Mateusz Naklicki <mateusz.naklicki@intel.com>
Signed-off-by: Francois Dugast <francois.dugast@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

include/uapi/drm/xe_drm.h

@@ -951,6 +951,30 @@ struct drm_xe_vm_bind_op {
 
 /**
  * struct drm_xe_vm_bind - Input of &DRM_IOCTL_XE_VM_BIND
+ *
+ * Below is an example of a minimal use of @drm_xe_vm_bind to
+ * asynchronously bind the buffer `data` at address `BIND_ADDRESS` to
+ * illustrate `userptr`. It can be synchronized by using the example
+ * provided for @drm_xe_sync.
+ *
+ * .. code-block:: C
+ *
+ *     data = aligned_alloc(ALIGNMENT, BO_SIZE);
+ *     struct drm_xe_vm_bind bind = {
+ *         .vm_id = vm,
+ *         .num_binds = 1,
+ *         .bind.obj = 0,
+ *         .bind.obj_offset = to_user_pointer(data),
+ *         .bind.range = BO_SIZE,
+ *         .bind.addr = BIND_ADDRESS,
+ *         .bind.op = DRM_XE_VM_BIND_OP_MAP_USERPTR,
+ *         .bind.flags = 0,
+ *         .num_syncs = 1,
+ *         .syncs = &sync,
+ *         .exec_queue_id = 0,
+ *     };
+ *     ioctl(fd, DRM_IOCTL_XE_VM_BIND, &bind);
+ *
  */
 struct drm_xe_vm_bind {
 	/** @extensions: Pointer to the first extension struct, if any */
@@ -1012,6 +1036,25 @@ struct drm_xe_vm_bind {
 
 /**
  * struct drm_xe_exec_queue_create - Input of &DRM_IOCTL_XE_EXEC_QUEUE_CREATE
+ *
+ * The example below shows how to use @drm_xe_exec_queue_create to create
+ * a simple exec_queue (no parallel submission) of class
+ * &DRM_XE_ENGINE_CLASS_RENDER.
+ *
+ * .. code-block:: C
+ *
+ *     struct drm_xe_engine_class_instance instance = {
+ *         .engine_class = DRM_XE_ENGINE_CLASS_RENDER,
+ *     };
+ *     struct drm_xe_exec_queue_create exec_queue_create = {
+ *          .extensions = 0,
+ *          .vm_id = vm,
+ *          .num_bb_per_exec = 1,
+ *          .num_eng_per_bb = 1,
+ *          .instances = to_user_pointer(&instance),
+ *     };
+ *     ioctl(fd, DRM_IOCTL_XE_EXEC_QUEUE_CREATE, &exec_queue_create);
+ *
  */
 struct drm_xe_exec_queue_create {
 #define DRM_XE_EXEC_QUEUE_EXTENSION_SET_PROPERTY		0
@@ -1103,6 +1146,30 @@ struct drm_xe_exec_queue_get_property {
  *
  * and the @flags can be:
  *  - %DRM_XE_SYNC_FLAG_SIGNAL
+ *
+ * A minimal use of @drm_xe_sync looks like this:
+ *
+ * .. code-block:: C
+ *
+ *     struct drm_xe_sync sync = {
+ *         .flags = DRM_XE_SYNC_FLAG_SIGNAL,
+ *         .type = DRM_XE_SYNC_TYPE_SYNCOBJ,
+ *     };
+ *     struct drm_syncobj_create syncobj_create = { 0 };
+ *     ioctl(fd, DRM_IOCTL_SYNCOBJ_CREATE, &syncobj_create);
+ *     sync.handle = syncobj_create.handle;
+ *         ...
+ *         use of &sync in drm_xe_exec or drm_xe_vm_bind
+ *         ...
+ *     struct drm_syncobj_wait wait = {
+ *         .handles = &sync.handle,
+ *         .timeout_nsec = INT64_MAX,
+ *         .count_handles = 1,
+ *         .flags = 0,
+ *         .first_signaled = 0,
+ *         .pad = 0,
+ *     };
+ *     ioctl(fd, DRM_IOCTL_SYNCOBJ_WAIT, &wait);
  */
 struct drm_xe_sync {
 	/** @extensions: Pointer to the first extension struct, if any */
@@ -1145,6 +1212,23 @@ struct drm_xe_sync {
 
 /**
  * struct drm_xe_exec - Input of &DRM_IOCTL_XE_EXEC
+ *
+ * This is an example to use @drm_xe_exec for execution of the object
+ * at BIND_ADDRESS (see example in @drm_xe_vm_bind) by an exec_queue
+ * (see example in @drm_xe_exec_queue_create). It can be synchronized
+ * by using the example provided for @drm_xe_sync.
+ *
+ * .. code-block:: C
+ *
+ *     struct drm_xe_exec exec = {
+ *         .exec_queue_id = exec_queue,
+ *         .syncs = &sync,
+ *         .num_syncs = 1,
+ *         .address = BIND_ADDRESS,
+ *         .num_batch_buffer = 1,
+ *     };
+ *     ioctl(fd, DRM_IOCTL_XE_EXEC, &exec);
+ *
  */
 struct drm_xe_exec {
 	/** @extensions: Pointer to the first extension struct, if any */