Reland "i915: Add GBM_BO_USE_HW_VIDEO_DECODER use flag"

This is a reland of 1bd7b04a3ae68c0314bdee06c559093de9e5a304

We've landed CL:1070995 which fixes the missing modifier that
caused tiling corruption on pre-KBL Intel devices and CL:1072638
which makes the failing vda unittests use SCANOUT_VDA_WRITE as
they were supposed to.

Original change's description:
> i915: Add GBM_BO_USE_HW_VIDEO_DECODER use flag
>
> This flag is used to indicate that the platform video decoder will be
> writing into this buffer and that it should be allocated
> accordingly. On Intel, this means that we have to allocate y-tiled
> NV12 for libva to be able to decode to the buffer.
>
> We force gralloc NV12 allocations to be linear for now, since ARC++
> doesn't properly pass modifiers to ChromeOS.
>
> BUG=822346
> TEST=test_that graphics_Gbm
>
> Change-Id: I840c30d22355d26816df718b49717407e2e4620f
> Reviewed-on: https://chromium-review.googlesource.com/996648
> Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
> Tested-by: Kristian H. Kristensen <hoegsberg@chromium.org>
> Reviewed-by: Kristian H. Kristensen <hoegsberg@chromium.org>

Bug: 822346
Change-Id: Icf0921dc91ac422da26371bffea34b26550b8234
Reviewed-on: https://chromium-review.googlesource.com/1073877
Commit-Ready: Kristian H. Kristensen <hoegsberg@chromium.org>
Tested-by: Kristian H. Kristensen <hoegsberg@chromium.org>
Reviewed-by: Kristian H. Kristensen <hoegsberg@chromium.org>
diff --git a/cros_gralloc/cros_gralloc_driver.cc b/cros_gralloc/cros_gralloc_driver.cc
index a68023e..31282bc 100644
--- a/cros_gralloc/cros_gralloc_driver.cc
+++ b/cros_gralloc/cros_gralloc_driver.cc
@@ -91,13 +91,23 @@
 	size_t num_planes;
 	uint32_t resolved_format;
 	uint32_t bytes_per_pixel;
+	uint64_t use_flags;
 
 	struct bo *bo;
 	struct cros_gralloc_handle *hnd;
 
 	resolved_format = drv_resolve_format(drv_, descriptor->drm_format, descriptor->use_flags);
+	use_flags = descriptor->use_flags;
+	/*
+	 * TODO(b/79682290): ARC++ assumes NV12 is always linear and doesn't
+	 * send modifiers across Wayland protocol, so we or in the
+	 * BO_USE_LINEAR flag here. We need to fix ARC++ to allocate and work
+	 * with tiled buffers.
+	 */
+	if (resolved_format == DRM_FORMAT_NV12)
+		use_flags |= BO_USE_LINEAR;
 	bo = drv_bo_create(drv_, descriptor->width, descriptor->height, resolved_format,
-			   descriptor->use_flags);
+			   use_flags);
 	if (!bo) {
 		drv_log("Failed to create bo.\n");
 		return -ENOMEM;
diff --git a/drv.h b/drv.h
index 9ca77d3..d27e845 100644
--- a/drv.h
+++ b/drv.h
@@ -37,6 +37,8 @@
 #define BO_USE_CAMERA_READ		(1ull << 14)
 #define BO_USE_RENDERSCRIPT		(1ull << 16)
 #define BO_USE_TEXTURE			(1ull << 17)
+#define BO_USE_HW_VIDEO_DECODER		(1ull << 18)
+
 
 /* Map flags */
 #define BO_MAP_NONE 0
diff --git a/gbm.h b/gbm.h
index da993c2..ce05ce3 100644
--- a/gbm.h
+++ b/gbm.h
@@ -265,6 +265,10 @@
    GBM_BO_USE_SW_READ_RARELY = (1 << 10),
    GBM_BO_USE_SW_WRITE_OFTEN = (1 << 11),
    GBM_BO_USE_SW_WRITE_RARELY = (1 << 12),
+   /**
+    * The buffer will be written by a video decode accelerator.
+    */
+   GBM_BO_USE_HW_VIDEO_DECODER = (1 << 13),
 };
 
 int
diff --git a/gbm_helpers.c b/gbm_helpers.c
index 2683669..81d1680 100644
--- a/gbm_helpers.c
+++ b/gbm_helpers.c
@@ -40,6 +40,8 @@
 		use_flags |= BO_USE_SW_WRITE_OFTEN;
 	if (usage & GBM_BO_USE_SW_WRITE_RARELY)
 		use_flags |= BO_USE_SW_WRITE_RARELY;
+	if (usage & GBM_BO_USE_HW_VIDEO_DECODER)
+		use_flags |= BO_USE_HW_VIDEO_DECODER;
 
 	return use_flags;
 }
diff --git a/i915.c b/i915.c
index 8e1871a..6df6dcc 100644
--- a/i915.c
+++ b/i915.c
@@ -101,6 +101,10 @@
 			combo->use_flags |= item->use_flags & ~BO_USE_CURSOR;
 		}
 
+		/* If we can scanout NV12, we support all tiling modes. */
+		if (item->format == DRM_FORMAT_NV12)
+			combo->use_flags |= item->use_flags;
+
 		if (combo->metadata.modifier == item->modifier)
 			combo->use_flags |= item->use_flags;
 	}
@@ -178,6 +182,11 @@
 			     ARRAY_SIZE(tileable_texture_source_formats), &metadata,
 			     texture_use_flags);
 
+	/* Support y-tiled NV12 for libva */
+	const uint32_t nv12_format = DRM_FORMAT_NV12;
+	drv_add_combinations(drv, &nv12_format, 1, &metadata,
+			     BO_USE_TEXTURE | BO_USE_HW_VIDEO_DECODER);
+
 	kms_items = drv_query_kms(drv);
 	if (!kms_items)
 		return 0;