vulkan/queue: Add a submit mode enum

This encapsulates all three possible submit modes: immediate, deferred,
and threaded.  It's more clear than the has_thread boolean combined with
device-level checks.

Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/15566>

src/vulkan/runtime/vk_queue.h

@@ -24,7 +24,7 @@
 #ifndef VK_QUEUE_H
 #define VK_QUEUE_H
 
-#include "vk_object.h"
+#include "vk_device.h"
 
 #include "c11/threads.h"
 
@@ -72,6 +72,22 @@ struct vk_queue {
                              struct vk_queue_submit *submit);
 
    struct {
+      /** Current submit mode
+       *
+       * This represents the exact current submit mode for this specific queue
+       * which may be different from `vk_device::submit_mode`.  In particular,
+       * this will never be `VK_QUEUE_SUBMIT_MODE_THREADED_ON_DEMAND`.
+       * Instead, when the device submit mode is
+       * `VK_QUEUE_SUBMIT_MODE_THREADED_ON_DEMAND`, the queue submit mode
+       * will be one of `VK_QUEUE_SUBMIT_MODE_THREADED` or
+       * `VK_QUEUE_SUBMIT_MODE_IMMEDIATE` depending on whether or not a submit
+       * thread is currently running for this queue.  If the device submit
+       * mode is `VK_QUEUE_SUBMIT_MODE_DEFERRED`, every queue in the device
+       * will use `VK_QUEUE_SUBMIT_MODE_DEFERRED` because the deferred submit
+       * model depends on regular flushing instead of independent threads.
+       */
+      enum vk_queue_submit_mode mode;
+
       mtx_t mutex;
       cnd_t push;
       cnd_t pop;
@@ -79,7 +95,6 @@ struct vk_queue {
       struct list_head submits;
 
       bool thread_run;
-      bool has_thread;
       thrd_t thread;
    } submit;