[PATCH] drm/tegra: add tiling FB modifiers

[Alexandre Courbot]

Add FB modifiers to allow user-space to specify that a surface is in one
of the two tiling formats supported by Tegra chips, and add support in
the tegradrm driver to handle them properly. This is necessary for the
display controller to directly display buffers generated by the GPU.

This feature is intended to replace the dedicated IOCTL enabled
by TEGRA_STAGING and to provide a non-staging alternative to that
solution.

Signed-off-by: Alexandre Courbot <acourbot@xxxxxxxxxx>
---
 drivers/gpu/drm/tegra/drm.c   |  2 ++
 drivers/gpu/drm/tegra/fb.c    | 23 +++++++++++++++++++---
 include/uapi/drm/drm_fourcc.h | 45 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 67 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c
index a9630c2d6cb3..36b4b30a5164 100644
--- a/drivers/gpu/drm/tegra/drm.c
+++ b/drivers/gpu/drm/tegra/drm.c
@@ -161,6 +161,8 @@ static int tegra_drm_load(struct drm_device *drm, unsigned long flags)
 	drm->mode_config.max_width = 4096;
 	drm->mode_config.max_height = 4096;
 
+	drm->mode_config.allow_fb_modifiers = true;
+
 	drm->mode_config.funcs = &tegra_drm_mode_funcs;
 
 	err = tegra_drm_fb_prepare(drm);
diff --git a/drivers/gpu/drm/tegra/fb.c b/drivers/gpu/drm/tegra/fb.c
index e6d71fa4028e..2fded58b2ca5 100644
--- a/drivers/gpu/drm/tegra/fb.c
+++ b/drivers/gpu/drm/tegra/fb.c
@@ -52,9 +52,26 @@ int tegra_fb_get_tiling(struct drm_framebuffer *framebuffer,
 			struct tegra_bo_tiling *tiling)
 {
 	struct tegra_fb *fb = to_tegra_fb(framebuffer);
-
-	/* TODO: handle YUV formats? */
-	*tiling = fb->planes[0]->tiling;
+	uint64_t modifier = fb->base.modifier[0];
+
+	switch (fourcc_mod_tegra_mod(modifier)) {
+	case NV_FORMAT_MOD_TEGRA_TILED:
+		tiling->mode = TEGRA_BO_TILING_MODE_TILED;
+		tiling->value = 0;
+		break;
+
+	case NV_FORMAT_MOD_TEGRA_16BX2_BLOCK(0):
+		tiling->mode = TEGRA_BO_TILING_MODE_BLOCK;
+		tiling->value = fourcc_mod_tegra_param(modifier);
+		if (tiling->value > 5)
+			return -EINVAL;
+		break;
+
+	default:
+		/* TODO: handle YUV formats? */
+		*tiling = fb->planes[0]->tiling;
+		break;
+	}
 
 	return 0;
 }
diff --git a/include/uapi/drm/drm_fourcc.h b/include/uapi/drm/drm_fourcc.h
index a5890bf44c0a..967dfab16881 100644
--- a/include/uapi/drm/drm_fourcc.h
+++ b/include/uapi/drm/drm_fourcc.h
@@ -233,6 +233,51 @@ extern "C" {
  */
 #define DRM_FORMAT_MOD_SAMSUNG_64_32_TILE	fourcc_mod_code(SAMSUNG, 1)
 
+
+/* NVIDIA Tegra frame buffer modifiers */
+
+/*
+ * Some modifiers take parameters, for example the number of vertical GOBs in
+ * a block. Reserve the lower 32 bits for parameters
+ */
+#define __fourcc_mod_tegra_mode_shift 32
+#define fourcc_mod_tegra_code(val, params) \
+	fourcc_mod_code(NV, ((((__u64)val) << __fourcc_mod_tegra_mode_shift) | params))
+#define fourcc_mod_tegra_mod(m) \
+	(m & ~((1ULL << __fourcc_mod_tegra_mode_shift) - 1))
+#define fourcc_mod_tegra_param(m) \
+	(m & ((1ULL << __fourcc_mod_tegra_mode_shift) - 1))
+
+/*
+ * Tegra Tiled Layout, used by Tegra 2, 3 and 4.
+ *
+ * Pixels are arranged in simple tiles of 16 x 16 bytes.
+ */
+#define NV_FORMAT_MOD_TEGRA_TILED fourcc_mod_tegra_code(1, 0)
+
+/*
+ * Tegra 16Bx2 Block Linear layout, used by TK1/TX1
+ *
+ * Pixels are arranged in 64x8 Groups Of Bytes (GOBs). GOBs are then stacked
+ * vertically by a power of 2 (1 to 32 GOBs) to form a block.
+ *
+ * Within a GOB, data is ordered as 16B x 2 lines sectors laid in Z-shape.
+ *
+ * Parameter 'v' is the log2 encoding of the number of GOBs stacked vertically.
+ * Valid values are:
+ *
+ * 0 == ONE_GOB
+ * 1 == TWO_GOBS
+ * 2 == FOUR_GOBS
+ * 3 == EIGHT_GOBS
+ * 4 == SIXTEEN_GOBS
+ * 5 == THIRTYTWO_GOBS
+ *
+ * Chapter 20 "Pixel Memory Formats" of the Tegra X1 TRM describes this format
+ * in full detail.
+ */
+#define NV_FORMAT_MOD_TEGRA_16BX2_BLOCK(v) fourcc_mod_tegra_code(2, v)
+
 #if defined(__cplusplus)
 }
 #endif
-- 
2.10.2