drm/xe/uapi: Document drm_xe_query_config keys

Provide a description of the keys used the struct
drm_xe_query_config info array.

Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/637
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>

Author: ifdu

include/uapi/drm/xe_drm.h

@@ -350,11 +350,31 @@ struct drm_xe_query_config {
 	/** @pad: MBZ */
 	__u32 pad;
 
+	/*
+	 * Device ID (lower 16 bits) and the device revision (next
+	 * 8 bits)
+	 */
 #define DRM_XE_QUERY_CONFIG_REV_AND_DEVICE_ID	0
+	/*
+	 * Flags describing the device configuration, see list below
+	 */
 #define DRM_XE_QUERY_CONFIG_FLAGS			1
+	/*
+	 * Flag is set if the device has usable VRAM
+	 */
 	#define DRM_XE_QUERY_CONFIG_FLAG_HAS_VRAM	(1 << 0)
+	/*
+	 * Minimal memory alignment required by this device,
+	 * typically SZ_4K or SZ_64K
+	 */
 #define DRM_XE_QUERY_CONFIG_MIN_ALIGNMENT		2
+	/*
+	 * Maximum bits of a virtual address
+	 */
 #define DRM_XE_QUERY_CONFIG_VA_BITS			3
+	/*
+	 * Value of the highest available exec queue priority
+	 */
 #define DRM_XE_QUERY_CONFIG_MAX_EXEC_QUEUE_PRIORITY	4
 	/** @info: array of elements containing the config info */
 	__u64 info[];