linux-kernel - [PATCH 1/3] gpu: ipu-v3: ipu-ic: Rename yuv2rgb encoding matrices

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Message-Id: <20190203194744.11546-2-slongerbeam@gmail.com>
Date:   Sun,  3 Feb 2019 11:47:42 -0800
From:   Steve Longerbeam <slongerbeam@...il.com>
To:     linux-media@...r.kernel.org
Cc:     Tim Harvey <tharvey@...eworks.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Steve Longerbeam <slongerbeam@...il.com>,
        dri-devel@...ts.freedesktop.org (open list:DRM DRIVERS FOR FREESCALE
        IMX), linux-kernel@...r.kernel.org (open list)
Subject: [PATCH 1/3] gpu: ipu-v3: ipu-ic: Rename yuv2rgb encoding matrices

The ycbcr2rgb and inverse rgb2ycbcr matrices define the BT.601 encoding
coefficients, so rename them to indicate that. And add some comments
to make clear these are BT.601 coefficients encoding between YUV limited
range and RGB full range. No functional changes.

Signed-off-by: Steve Longerbeam <slongerbeam@...il.com>
---
 drivers/gpu/ipu-v3/ipu-ic.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/ipu-v3/ipu-ic.c b/drivers/gpu/ipu-v3/ipu-ic.c
index 594c3cbc8291..35ae86ff0585 100644
--- a/drivers/gpu/ipu-v3/ipu-ic.c
+++ b/drivers/gpu/ipu-v3/ipu-ic.c
@@ -183,11 +183,13 @@ struct ic_csc_params {
 };
 
 /*
+ * BT.601 encoding from RGB full range to YUV limited range:
+ *
  * Y = R *  .299 + G *  .587 + B *  .114;
  * U = R * -.169 + G * -.332 + B *  .500 + 128.;
  * V = R *  .500 + G * -.419 + B * -.0813 + 128.;
  */
-static const struct ic_csc_params ic_csc_rgb2ycbcr = {
+static const struct ic_csc_params ic_csc_rgb2ycbcr_bt601 = {
 	.coeff = {
 		{ 77, 150, 29 },
 		{ 469, 427, 128 },
@@ -208,11 +210,13 @@ static const struct ic_csc_params ic_csc_rgb2rgb = {
 };
 
 /*
+ * Inverse BT.601 encoding from YUV limited range to RGB full range:
+ *
  * R = (1.164 * (Y - 16)) + (1.596 * (Cr - 128));
  * G = (1.164 * (Y - 16)) - (0.392 * (Cb - 128)) - (0.813 * (Cr - 128));
  * B = (1.164 * (Y - 16)) + (2.017 * (Cb - 128);
  */
-static const struct ic_csc_params ic_csc_ycbcr2rgb = {
+static const struct ic_csc_params ic_csc_ycbcr2rgb_bt601 = {
 	.coeff = {
 		{ 149, 0, 204 },
 		{ 149, 462, 408 },
@@ -238,9 +242,9 @@ static int init_csc(struct ipu_ic *ic,
 		(priv->tpmem_base + ic->reg->tpmem_csc[csc_index]);
 
 	if (inf == IPUV3_COLORSPACE_YUV && outf == IPUV3_COLORSPACE_RGB)
-		params = &ic_csc_ycbcr2rgb;
+		params = &ic_csc_ycbcr2rgb_bt601;
 	else if (inf == IPUV3_COLORSPACE_RGB && outf == IPUV3_COLORSPACE_YUV)
-		params = &ic_csc_rgb2ycbcr;
+		params = &ic_csc_rgb2ycbcr_bt601;
 	else if (inf == IPUV3_COLORSPACE_RGB && outf == IPUV3_COLORSPACE_RGB)
 		params = &ic_csc_rgb2rgb;
 	else {
-- 
2.17.1