habanalabs: add comments in uapi/misc/habanalabs.h

Add comment about minimum and maximum size of command buffer.
Add some text about the expected input of CS IOCTL.
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

include/uapi/misc/habanalabs.h

@@ -112,7 +112,9 @@ struct hl_cb_in {
 	__u64 cb_handle;
 	/* HL_CB_OP_* */
 	__u32 op;
-	/* Size of CB. Minimum requested size must be PAGE_SIZE */
+	/* Size of CB. Maximum size is 2MB. The minimum size that will be
+	 * allocated, regardless of this parameter's value, is PAGE_SIZE
+	 */
 	__u32 cb_size;
 	/* Context ID - Currently not in use */
 	__u32 ctx_id;
@@ -364,6 +366,12 @@ union hl_mem_args {
  * internal. The driver will get completion notifications from the device only
  * on JOBS which are enqueued in the external queues.
  *
+ * For jobs on external queues, the user needs to create command buffers
+ * through the CB ioctl and give the CB's handle to the CS ioctl. For jobs on
+ * internal queues, the user needs to prepare a "command buffer" with packets
+ * on either the SRAM or DRAM, and give the device address of that buffer to
+ * the CS ioctl.
+ *
  * This IOCTL is asynchronous in regard to the actual execution of the CS. This
  * means it returns immediately after ALL the JOBS were enqueued on their
  * relevant queues. Therefore, the user mustn't assume the CS has been completed