Re: [PATCH v3 3/4] gpu: ipu-v3: ipu-ic: Add support for BT.709 encoding

Pass v4l2 encoding enum to the ipu_ic task init functions, and add
support for the BT.709 encoding and inverse encoding matrices.

Reported-by: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Steve Longerbeam <slongerbeam@gmail.com>
---
Changes in v2:
- only return "Unsupported YCbCr encoding" error if inf != outf,
  since if inf = outf, the identity matrix can be used. Reported
  by Tim Harvey.
---
 drivers/gpu/ipu-v3/ipu-ic.c                 | 71 +++++++++++++++++++--
 drivers/gpu/ipu-v3/ipu-image-convert.c      |  1 +
 drivers/staging/media/imx/imx-ic-prpencvf.c |  4 +-
 include/video/imx-ipu-v3.h                  |  5 +-
 4 files changed, 71 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/ipu-v3/ipu-ic.c b/drivers/gpu/ipu-v3/ipu-ic.c
index e459615a49a1..0d57ca7ba18e 100644
--- a/drivers/gpu/ipu-v3/ipu-ic.c
+++ b/drivers/gpu/ipu-v3/ipu-ic.c

@@ -212,6 +212,23 @@ static const struct ic_csc_params ic_csc_identity = {
        .scale = 2,
 };

+/*
+ * BT.709 encoding from RGB full range to YUV limited range:
+ *
+ * Y = R *  .2126 + G *  .7152 + B *  .0722;
+ * U = R * -.1146 + G * -.3854 + B *  .5000 + 128.;
+ * V = R *  .5000 + G * -.4542 + B * -.0458 + 128.;
+ */
+static const struct ic_csc_params ic_csc_rgb2ycbcr_bt709 = {
+       .coeff = {
+               { 54, 183, 18 },
+               { 483, 413, 128 },
+               { 128, 396, 500 },
+       },
+       .offset = { 0, 512, 512 },
+       .scale = 1,
+};
+
 /*
  * Inverse BT.601 encoding from YUV limited range to RGB full range:
  *

@@ -229,12 +246,31 @@ static const struct ic_csc_params ic_csc_ycbcr2rgb_bt601 = {
        .scale = 2,
 };

+/*
+ * Inverse BT.709 encoding from YUV limited range to RGB full range:
+ *
+ * R = (1. * (Y - 16)) + (1.5748 * (Cr - 128));
+ * G = (1. * (Y - 16)) - (0.1873 * (Cb - 128)) - (0.4681 * (Cr - 128));
+ * B = (1. * (Y - 16)) + (1.8556 * (Cb - 128);
+ */
+static const struct ic_csc_params ic_csc_ycbcr2rgb_bt709 = {
+       .coeff = {
+               { 128, 0, 202 },
+               { 128, 488, 452 },
+               { 128, 238, 0 },
+       },
+       .offset = { -435, 136, -507 },
+       .scale = 2,
+};
+
 static int init_csc(struct ipu_ic *ic,
                    enum ipu_color_space inf,
                    enum ipu_color_space outf,
+                   enum v4l2_ycbcr_encoding encoding,
                    int csc_index)
 {
        struct ipu_ic_priv *priv = ic->priv;
+       const struct ic_csc_params *params_rgb2yuv, *params_yuv2rgb;
        const struct ic_csc_params *params;
        u32 __iomem *base;
        const u16 (*c)[3];

@@ -244,12 +280,30 @@ static int init_csc(struct ipu_ic *ic,
        base = (u32 __iomem *)
                (priv->tpmem_base + ic->reg->tpmem_csc[csc_index]);

+       switch (encoding) {
+       case V4L2_YCBCR_ENC_601:
+               params_rgb2yuv =  &ic_csc_rgb2ycbcr_bt601;
+               params_yuv2rgb = &ic_csc_ycbcr2rgb_bt601;
+               break;
+       case V4L2_YCBCR_ENC_709:
+               params_rgb2yuv =  &ic_csc_rgb2ycbcr_bt709;
+               params_yuv2rgb = &ic_csc_ycbcr2rgb_bt709;
+               break;
+       default:
+               if (inf != outf) {
+                       dev_err(priv->ipu->dev,
+                               "Unsupported YCbCr encoding\n");
+                       return -EINVAL;
+               }
+               break;
+       }
+
        if (inf = outf)
                params = &ic_csc_identity;
        else if (inf = IPUV3_COLORSPACE_YUV)
-               params = &ic_csc_ycbcr2rgb_bt601;
+               params = &ic_csc_ycbcr2rgb;

        else
-               params = &ic_csc_rgb2ycbcr_bt601;
+               params = &ic_csc_rgb2ycbcr;