drm/tegra: Use tegra_dev_iommu_get_stream_id()

Use the newly implemented tegra_dev_iommu_get_stream_id() helper to
encapsulate and centralize the IOMMU stream ID access.
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/gpu/drm/tegra/submit.c

@@ -609,21 +609,13 @@ int tegra_drm_ioctl_channel_submit(struct drm_device *drm, void *data,
 			host1x_memory_context_get(job->memory_context);
 		}
 	} else if (context->client->ops->get_streamid_offset) {
-#ifdef CONFIG_IOMMU_API
-		struct iommu_fwspec *spec;
-
 		/*
 		 * Job submission will need to temporarily change stream ID,
 		 * so need to tell it what to change it back to.
 		 */
-		spec = dev_iommu_fwspec_get(context->client->base.dev);
-		if (spec && spec->num_ids > 0)
-			job->engine_fallback_streamid = spec->ids[0] & 0xffff;
-		else
-			job->engine_fallback_streamid = 0x7f;
-#else
-		job->engine_fallback_streamid = 0x7f;
-#endif
+		if (!tegra_dev_iommu_get_stream_id(context->client->base.dev,
+						   &job->engine_fallback_streamid))
+			job->engine_fallback_streamid = TEGRA_STREAM_ID_BYPASS;
 	}
 
 	/* Boot engine. */