drm/i915/guc: Wait for ucode DMA transfer completion

We silently assumed that DMA transfer will be completed
within assumed timeout and thus we were waiting only at
last step for GuC to become ready. Add intermediate wait
to catch unexpected delays in DMA transfer.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Sagar Arun Kamble <sagar.a.kamble@intel.com>
Reviewed-by: Sagar Arun Kamble <sagar.a.kamble@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171103151816.62048-2-michal.wajdeczko@intel.com
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

drivers/gpu/drm/i915/intel_guc_fw.c

@@ -160,6 +160,8 @@ static int guc_xfer_ucode(struct intel_guc *guc, struct i915_vma *vma)
 	struct drm_i915_private *dev_priv = guc_to_i915(guc);
 	struct intel_uc_fw *guc_fw = &guc->fw;
 	unsigned long offset;
+	u32 status;
+	int ret;
 
 	/*
 	 * The header plus uCode will be copied to WOPCM via DMA, excluding any
@@ -182,7 +184,12 @@ static int guc_xfer_ucode(struct intel_guc *guc, struct i915_vma *vma)
 	/* Finally start the DMA */
 	I915_WRITE(DMA_CTRL, _MASKED_BIT_ENABLE(UOS_MOVE | START_DMA));
 
-	return 0;
+	/* Wait for DMA to finish */
+	ret = __intel_wait_for_register_fw(dev_priv, DMA_CTRL, START_DMA, 0,
+					   2, 100, &status);
+	DRM_DEBUG_DRIVER("GuC DMA status %#x\n", status);
+
+	return ret;
 }
 
 /*