drm/i915: Enable Resource Streamer state save/restore on MI_SET_CONTEXT

Also clarify comments on context size that the extra state for
Resource Streamer is included.

v2: Don't remove the extended save/restore enabled for older
    platforms. (Ville)
    Use new MI_SET_CONTEXT defines for HSW RS save/restore state
    instead of extended save/restore. (Daniel)
Suggested-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Abdiel Janulgue <abdiel.janulgue@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_gem_context.c

@@ -501,7 +501,9 @@ mi_set_context(struct drm_i915_gem_request *req, u32 hw_flags)
 	}
 
 	/* These flags are for resource streamer on HSW+ */
-	if (!IS_HASWELL(ring->dev) && INTEL_INFO(ring->dev)->gen < 8)
+	if (IS_HASWELL(ring->dev) || INTEL_INFO(ring->dev)->gen >= 8)
+		flags |= (HSW_MI_RS_SAVE_STATE_EN | HSW_MI_RS_RESTORE_STATE_EN);
+	else if (INTEL_INFO(ring->dev)->gen < 8)
 		flags |= (MI_SAVE_EXT_STATE_EN | MI_RESTORE_EXT_STATE_EN);
 
 

drivers/gpu/drm/i915/i915_reg.h

@@ -321,6 +321,8 @@
 #define   MI_RESTORE_EXT_STATE_EN	(1<<2)
 #define   MI_FORCE_RESTORE		(1<<1)
 #define   MI_RESTORE_INHIBIT		(1<<0)
+#define   HSW_MI_RS_SAVE_STATE_EN       (1<<3)
+#define   HSW_MI_RS_RESTORE_STATE_EN    (1<<2)
 #define MI_SEMAPHORE_SIGNAL	MI_INSTR(0x1b, 0) /* GEN8+ */
 #define   MI_SEMAPHORE_TARGET(engine)	((engine)<<15)
 #define MI_SEMAPHORE_WAIT	MI_INSTR(0x1c, 2) /* GEN8+ */
@@ -2803,7 +2805,8 @@ enum skl_disp_power_wells {
  * valid. Now, docs explain in dwords what is in the context object. The full
  * size is 70720 bytes, however, the power context and execlist context will
  * never be saved (power context is stored elsewhere, and execlists don't work
- * on HSW) - so the final size is 66944 bytes, which rounds to 17 pages.
+ * on HSW) - so the final size, including the extra state required for the
+ * Resource Streamer, is 66944 bytes, which rounds to 17 pages.
  */
 #define HSW_CXT_TOTAL_SIZE		(17 * PAGE_SIZE)
 /* Same as Haswell, but 72064 bytes now. */