drm/vc4: Extend BROADCOM_SAND modifier to handle computing automatically

The vc4 HVS can handle almost any column height in the SAND format,
and this was signalled via the vendor bits in DRM_FORMAT_MOD_BROADCOM_SAND128.

DRM is now requiring that all potential modifier values are reported,
not just the canonical version of them.
It is not feasible to report all the potential column heights,
therefore add an option to go for a lowest common denominator
calculation that computes the column height as height * 3/2 as
it is YUV420.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>

Author: 6by9

drivers/gpu/drm/vc4/vc4_plane.c

@@ -1248,6 +1248,9 @@ static int vc4_plane_mode_set(struct drm_plane *plane,
 	case DRM_FORMAT_MOD_BROADCOM_SAND256: {
 		uint32_t param = fourcc_mod_broadcom_param(fb->modifier);
 
+		if (param == SAND_AUTO_HEIGHT)
+			param = (fb->height * 3) >> 1;
+
 		if (param > SCALER_TILE_HEIGHT_MASK) {
 			DRM_DEBUG_KMS("SAND height too large (%d)\n",
 				      param);
@@ -1711,6 +1714,9 @@ static int vc6_plane_mode_set(struct drm_plane *plane,
 		u32 starting_offset;
 		u32 fetch_count;
 
+		if (param == SAND_AUTO_HEIGHT)
+			param = (fb->height * 3) >> 1;
+
 		if (param > SCALER_TILE_HEIGHT_MASK) {
 			DRM_DEBUG_KMS("SAND height too large (%d)\n",
 				      param);
@@ -2395,8 +2401,11 @@ struct drm_plane *vc4_plane_init(struct drm_device *dev,
 	static const uint64_t modifiers[] = {
 		DRM_FORMAT_MOD_BROADCOM_VC4_T_TILED,
 		DRM_FORMAT_MOD_BROADCOM_SAND128,
+		DRM_FORMAT_MOD_BROADCOM_SAND128_AUTO_HEIGHT,
 		DRM_FORMAT_MOD_BROADCOM_SAND64,
+		DRM_FORMAT_MOD_BROADCOM_SAND64_AUTO_HEIGHT,
 		DRM_FORMAT_MOD_BROADCOM_SAND256,
+		DRM_FORMAT_MOD_BROADCOM_SAND256_AUTO_HEIGHT,
 		DRM_FORMAT_MOD_LINEAR,
 		DRM_FORMAT_MOD_INVALID
 	};

include/uapi/drm/drm_fourcc.h

@@ -1035,6 +1035,14 @@ drm_fourcc_canonicalize_nvidia_format_mod(__u64 modifier)
  * to various core checks that look at it , so you should set the
  * stride to width*cpp).
  *
+ * As DRM is now mandating that all modifiers must be reported, not
+ * just the canonical version, the use of
+ * DRM_FORMAT_MOD_BROADCOM_SANDxx_COL_HEIGHT(DRM_MODIFIER_SAND_AUTO_HEIGHT)
+ * is used to make the driver derive the column height as
+ * image_height * 3 / 2 lines as it is a YUV4:2:0 image.
+ * The old explicit specification of column height is still accepted, but
+ * is not reported other than in canonicalised form.
+ *
  * Note that the column height for this format modifier is the same
  * for all of the planes, assuming that each column contains both Y
  * and UV.  Some SAND-using hardware stores UV in a separate tiled
@@ -1046,6 +1054,8 @@ drm_fourcc_canonicalize_nvidia_format_mod(__u64 modifier)
  * wide, but as this is a 10 bpp format that translates to 96 pixels.
  */
 
+#define SAND_AUTO_HEIGHT	0x7fffffffULL
+
 #define DRM_FORMAT_MOD_BROADCOM_SAND32_COL_HEIGHT(v) \
 	fourcc_mod_broadcom_code(2, v)
 #define DRM_FORMAT_MOD_BROADCOM_SAND64_COL_HEIGHT(v) \
@@ -1057,12 +1067,20 @@ drm_fourcc_canonicalize_nvidia_format_mod(__u64 modifier)
 
 #define DRM_FORMAT_MOD_BROADCOM_SAND32 \
 	DRM_FORMAT_MOD_BROADCOM_SAND32_COL_HEIGHT(0)
+#define DRM_FORMAT_MOD_BROADCOM_SAND32_AUTO_HEIGHT \
+	DRM_FORMAT_MOD_BROADCOM_SAND32_COL_HEIGHT(SAND_AUTO_HEIGHT)
 #define DRM_FORMAT_MOD_BROADCOM_SAND64 \
 	DRM_FORMAT_MOD_BROADCOM_SAND64_COL_HEIGHT(0)
+#define DRM_FORMAT_MOD_BROADCOM_SAND64_AUTO_HEIGHT \
+	DRM_FORMAT_MOD_BROADCOM_SAND64_COL_HEIGHT(SAND_AUTO_HEIGHT)
 #define DRM_FORMAT_MOD_BROADCOM_SAND128 \
 	DRM_FORMAT_MOD_BROADCOM_SAND128_COL_HEIGHT(0)
+#define DRM_FORMAT_MOD_BROADCOM_SAND128_AUTO_HEIGHT \
+	DRM_FORMAT_MOD_BROADCOM_SAND128_COL_HEIGHT(SAND_AUTO_HEIGHT)
 #define DRM_FORMAT_MOD_BROADCOM_SAND256 \
 	DRM_FORMAT_MOD_BROADCOM_SAND256_COL_HEIGHT(0)
+#define DRM_FORMAT_MOD_BROADCOM_SAND256_AUTO_HEIGHT \
+	DRM_FORMAT_MOD_BROADCOM_SAND256_COL_HEIGHT(SAND_AUTO_HEIGHT)
 
 /* Broadcom UIF format
  *