New SoCs, like MT8195, not only may support bigger lookup tables, but
have got a different register layout to support bigger precision:
support specifying the number of `lut_bits` for each SoC and use it
in mtk_gamma_set_common() to perform the right calculations and add
support for 12-bit gamma lookup tables.

While at it, also reorder the variables in mtk_gamma_set_common()
and rename `lut_base` to `lut0_base` to improve readability.

Reviewed-by: Jason-JH.Lin <jason-jh.lin@mediatek.com>
Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com>
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
---
 drivers/gpu/drm/mediatek/mtk_disp_gamma.c | 83 +++++++++++++++++------
 1 file changed, 64 insertions(+), 19 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_disp_gamma.c b/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
index 911468984ad5..6305cd95e6d4 100644
--- a/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
+++ b/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
@@ -26,17 +26,26 @@
 #define DISP_GAMMA_SIZE_VSIZE				GENMASK(12, 0)
 #define DISP_GAMMA_BANK				0x0100
 #define DISP_GAMMA_BANK_BANK				GENMASK(1, 0)
+#define DISP_GAMMA_BANK_DATA_MODE			BIT(2)
 #define DISP_GAMMA_LUT				0x0700
+#define DISP_GAMMA_LUT1				0x0b00
 
+/* For 10 bit LUT layout, R/G/B are in the same register */
 #define DISP_GAMMA_LUT_10BIT_R			GENMASK(29, 20)
 #define DISP_GAMMA_LUT_10BIT_G			GENMASK(19, 10)
 #define DISP_GAMMA_LUT_10BIT_B			GENMASK(9, 0)
 
+/* For 12 bit LUT layout, R/G are in LUT, B is in LUT1 */
+#define DISP_GAMMA_LUT_12BIT_R			GENMASK(11, 0)
+#define DISP_GAMMA_LUT_12BIT_G			GENMASK(23, 12)
+#define DISP_GAMMA_LUT_12BIT_B			GENMASK(11, 0)
+
 struct mtk_disp_gamma_data {
 	bool has_dither;
 	bool lut_diff;
 	u16 lut_bank_size;
 	u16 lut_size;
+	u8 lut_bits;
 };
 
 /*
@@ -72,28 +81,48 @@ unsigned int mtk_gamma_get_lut_size(struct device *dev)
 	return 0;
 }
 
+/*
+ * SoCs supporting 12-bits LUTs are using a new register layout that does
+ * always support (by HW) both 12-bits and 10-bits LUT but, on those, we
+ * ignore the support for 10-bits in this driver and always use 12-bits.
+ *
+ * Summarizing:
+ * - SoC HW support 9/10-bits LUT only
+ *   - Old register layout
+ *     - 10-bits LUT supported
+ *     - 9-bits LUT not supported
+ * - SoC HW support both 10/12bits LUT
+ *   - New register layout
+ *     - 12-bits LUT supported
+ *     - 10-its LUT not supported
+ */
 void mtk_gamma_set(struct device *dev, struct drm_crtc_state *state)
 {
 	struct mtk_disp_gamma *gamma = dev_get_drvdata(dev);
-	unsigned int i;
-	struct drm_color_lut *lut;
-	void __iomem *lut_base;
-	u32 cfg_val, lbank_val, word;
+	void __iomem *lut0_base = gamma->regs + DISP_GAMMA_LUT;
+	void __iomem *lut1_base = gamma->regs + DISP_GAMMA_LUT1;
+	u32 cfg_val, data_mode, lbank_val, word[2];
+	u8 lut_bits = gamma->data->lut_bits;
 	int cur_bank, num_lut_banks;
+	struct drm_color_lut *lut;
+	unsigned int i;
 
 	/* If there's no gamma lut there's nothing to do here. */
 	if (!state->gamma_lut)
 		return;
 
 	num_lut_banks = gamma->data->lut_size / gamma->data->lut_bank_size;
-	lut_base = gamma->regs + DISP_GAMMA_LUT;
 	lut = (struct drm_color_lut *)state->gamma_lut->data;
 
+	/* Switch to 12 bits data mode if supported */
+	data_mode = FIELD_PREP(DISP_GAMMA_BANK_DATA_MODE, !!(lut_bits == 12));
+
 	for (cur_bank = 0; cur_bank < num_lut_banks; cur_bank++) {
 
 		/* Switch gamma bank and set data mode before writing LUT */
 		if (num_lut_banks > 1) {
 			lbank_val = FIELD_PREP(DISP_GAMMA_BANK_BANK, cur_bank);
+			lbank_val |= data_mode;
 			writel(lbank_val, gamma->regs + DISP_GAMMA_BANK);
 		}
 
@@ -101,29 +130,43 @@ void mtk_gamma_set(struct device *dev, struct drm_crtc_state *state)
 			int n = cur_bank * gamma->data->lut_bank_size + i;
 			struct drm_color_lut diff, hwlut;
 
-			hwlut.red = drm_color_lut_extract(lut[n].red, 10);
-			hwlut.green = drm_color_lut_extract(lut[n].green, 10);
-			hwlut.blue = drm_color_lut_extract(lut[n].blue, 10);
+			hwlut.red = drm_color_lut_extract(lut[n].red, lut_bits);
+			hwlut.green = drm_color_lut_extract(lut[n].green, lut_bits);
+			hwlut.blue = drm_color_lut_extract(lut[n].blue, lut_bits);
 
 			if (!gamma->data->lut_diff || (i % 2 == 0)) {
-				word = FIELD_PREP(DISP_GAMMA_LUT_10BIT_R, hwlut.red);
-				word |= FIELD_PREP(DISP_GAMMA_LUT_10BIT_G, hwlut.green);
-				word |= FIELD_PREP(DISP_GAMMA_LUT_10BIT_B, hwlut.blue);
+				if (lut_bits == 12) {
+					word[0] = FIELD_PREP(DISP_GAMMA_LUT_12BIT_R, hwlut.red);
+					word[0] |= FIELD_PREP(DISP_GAMMA_LUT_12BIT_G, hwlut.green);
+					word[1] = FIELD_PREP(DISP_GAMMA_LUT_12BIT_B, hwlut.blue);
+				} else {
+					word[0] = FIELD_PREP(DISP_GAMMA_LUT_10BIT_R, hwlut.red);
+					word[0] |= FIELD_PREP(DISP_GAMMA_LUT_10BIT_G, hwlut.green);
+					word[0] |= FIELD_PREP(DISP_GAMMA_LUT_10BIT_B, hwlut.blue);
+				}
 			} else {
 				diff.red = lut[n].red - lut[n - 1].red;
-				diff.red = drm_color_lut_extract(diff.red, 10);
+				diff.red = drm_color_lut_extract(diff.red, lut_bits);
 
 				diff.green = lut[n].green - lut[n - 1].green;
-				diff.green = drm_color_lut_extract(diff.green, 10);
+				diff.green = drm_color_lut_extract(diff.green, lut_bits);
 
 				diff.blue = lut[n].blue - lut[n - 1].blue;
-				diff.blue = drm_color_lut_extract(diff.blue, 10);
-
-				word = FIELD_PREP(DISP_GAMMA_LUT_10BIT_R, diff.red);
-				word |= FIELD_PREP(DISP_GAMMA_LUT_10BIT_G, diff.green);
-				word |= FIELD_PREP(DISP_GAMMA_LUT_10BIT_B, diff.blue);
+				diff.blue = drm_color_lut_extract(diff.blue, lut_bits);
+
+				if (lut_bits == 12) {
+					word[0] = FIELD_PREP(DISP_GAMMA_LUT_12BIT_R, diff.red);
+					word[0] |= FIELD_PREP(DISP_GAMMA_LUT_12BIT_G, diff.green);
+					word[1] = FIELD_PREP(DISP_GAMMA_LUT_12BIT_B, diff.blue);
+				} else {
+					word[0] = FIELD_PREP(DISP_GAMMA_LUT_10BIT_R, diff.red);
+					word[0] |= FIELD_PREP(DISP_GAMMA_LUT_10BIT_G, diff.green);
+					word[0] |= FIELD_PREP(DISP_GAMMA_LUT_10BIT_B, diff.blue);
+				}
 			}
-			writel(word, lut_base + i * 4);
+			writel(word[0], lut0_base + i * 4);
+			if (lut_bits == 12)
+				writel(word[1], lut1_base + i * 4);
 		}
 	}
 
@@ -225,11 +268,13 @@ static void mtk_disp_gamma_remove(struct platform_device *pdev)
 static const struct mtk_disp_gamma_data mt8173_gamma_driver_data = {
 	.has_dither = true,
 	.lut_bank_size = 512,
+	.lut_bits = 10,
 	.lut_size = 512,
 };
 
 static const struct mtk_disp_gamma_data mt8183_gamma_driver_data = {
 	.lut_bank_size = 512,
+	.lut_bits = 10,
 	.lut_diff = true,
 	.lut_size = 512,
 };
-- 
2.42.0

Hi, Angelo:

On Thu, 2023-10-12 at 11:57 +0200, AngeloGioacchino Del Regno wrote:
> New SoCs, like MT8195, not only may support bigger lookup tables, but
> have got a different register layout to support bigger precision:
> support specifying the number of `lut_bits` for each SoC and use it
> in mtk_gamma_set_common() to perform the right calculations and add
> support for 12-bit gamma lookup tables.
> 
> While at it, also reorder the variables in mtk_gamma_set_common()
> and rename `lut_base` to `lut0_base` to improve readability.

Reviewed-by: CK Hu <ck.hu@mediatek.com>

> 
> Reviewed-by: Jason-JH.Lin <jason-jh.lin@mediatek.com>
> Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com>
> Signed-off-by: AngeloGioacchino Del Regno <
> angelogioacchino.delregno@collabora.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_disp_gamma.c | 83 +++++++++++++++++--
> ----
>  1 file changed, 64 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
> b/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
> index 911468984ad5..6305cd95e6d4 100644
> --- a/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
> +++ b/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
> @@ -26,17 +26,26 @@
>  #define DISP_GAMMA_SIZE_VSIZE				GENMASK
> (12, 0)
>  #define DISP_GAMMA_BANK				0x0100
>  #define DISP_GAMMA_BANK_BANK				GENMASK(1, 0)
> +#define DISP_GAMMA_BANK_DATA_MODE			BIT(2)
>  #define DISP_GAMMA_LUT				0x0700
> +#define DISP_GAMMA_LUT1				0x0b00
>  
> +/* For 10 bit LUT layout, R/G/B are in the same register */
>  #define DISP_GAMMA_LUT_10BIT_R			GENMASK(29, 20)
>  #define DISP_GAMMA_LUT_10BIT_G			GENMASK(19, 10)
>  #define DISP_GAMMA_LUT_10BIT_B			GENMASK(9, 0)
>  
> +/* For 12 bit LUT layout, R/G are in LUT, B is in LUT1 */
> +#define DISP_GAMMA_LUT_12BIT_R			GENMASK(11, 0)
> +#define DISP_GAMMA_LUT_12BIT_G			GENMASK(23, 12)
> +#define DISP_GAMMA_LUT_12BIT_B			GENMASK(11, 0)
> +
>  struct mtk_disp_gamma_data {
>  	bool has_dither;
>  	bool lut_diff;
>  	u16 lut_bank_size;
>  	u16 lut_size;
> +	u8 lut_bits;
>  };
>  
>  /*
> @@ -72,28 +81,48 @@ unsigned int mtk_gamma_get_lut_size(struct device
> *dev)
>  	return 0;
>  }
>  
> +/*
> + * SoCs supporting 12-bits LUTs are using a new register layout that
> does
> + * always support (by HW) both 12-bits and 10-bits LUT but, on
> those, we
> + * ignore the support for 10-bits in this driver and always use 12-
> bits.
> + *
> + * Summarizing:
> + * - SoC HW support 9/10-bits LUT only
> + *   - Old register layout
> + *     - 10-bits LUT supported
> + *     - 9-bits LUT not supported
> + * - SoC HW support both 10/12bits LUT
> + *   - New register layout
> + *     - 12-bits LUT supported
> + *     - 10-its LUT not supported
> + */
>  void mtk_gamma_set(struct device *dev, struct drm_crtc_state *state)
>  {
>  	struct mtk_disp_gamma *gamma = dev_get_drvdata(dev);
> -	unsigned int i;
> -	struct drm_color_lut *lut;
> -	void __iomem *lut_base;
> -	u32 cfg_val, lbank_val, word;
> +	void __iomem *lut0_base = gamma->regs + DISP_GAMMA_LUT;
> +	void __iomem *lut1_base = gamma->regs + DISP_GAMMA_LUT1;
> +	u32 cfg_val, data_mode, lbank_val, word[2];
> +	u8 lut_bits = gamma->data->lut_bits;
>  	int cur_bank, num_lut_banks;
> +	struct drm_color_lut *lut;
> +	unsigned int i;
>  
>  	/* If there's no gamma lut there's nothing to do here. */
>  	if (!state->gamma_lut)
>  		return;
>  
>  	num_lut_banks = gamma->data->lut_size / gamma->data-
> >lut_bank_size;
> -	lut_base = gamma->regs + DISP_GAMMA_LUT;
>  	lut = (struct drm_color_lut *)state->gamma_lut->data;
>  
> +	/* Switch to 12 bits data mode if supported */
> +	data_mode = FIELD_PREP(DISP_GAMMA_BANK_DATA_MODE, !!(lut_bits
> == 12));
> +
>  	for (cur_bank = 0; cur_bank < num_lut_banks; cur_bank++) {
>  
>  		/* Switch gamma bank and set data mode before writing
> LUT */
>  		if (num_lut_banks > 1) {
>  			lbank_val = FIELD_PREP(DISP_GAMMA_BANK_BANK,
> cur_bank);
> +			lbank_val |= data_mode;
>  			writel(lbank_val, gamma->regs +
> DISP_GAMMA_BANK);
>  		}
>  
> @@ -101,29 +130,43 @@ void mtk_gamma_set(struct device *dev, struct
> drm_crtc_state *state)
>  			int n = cur_bank * gamma->data->lut_bank_size +
> i;
>  			struct drm_color_lut diff, hwlut;
>  
> -			hwlut.red = drm_color_lut_extract(lut[n].red,
> 10);
> -			hwlut.green =
> drm_color_lut_extract(lut[n].green, 10);
> -			hwlut.blue = drm_color_lut_extract(lut[n].blue,
> 10);
> +			hwlut.red = drm_color_lut_extract(lut[n].red,
> lut_bits);
> +			hwlut.green =
> drm_color_lut_extract(lut[n].green, lut_bits);
> +			hwlut.blue = drm_color_lut_extract(lut[n].blue,
> lut_bits);
>  
>  			if (!gamma->data->lut_diff || (i % 2 == 0)) {
> -				word =
> FIELD_PREP(DISP_GAMMA_LUT_10BIT_R, hwlut.red);
> -				word |=
> FIELD_PREP(DISP_GAMMA_LUT_10BIT_G, hwlut.green);
> -				word |=
> FIELD_PREP(DISP_GAMMA_LUT_10BIT_B, hwlut.blue);
> +				if (lut_bits == 12) {
> +					word[0] =
> FIELD_PREP(DISP_GAMMA_LUT_12BIT_R, hwlut.red);
> +					word[0] |=
> FIELD_PREP(DISP_GAMMA_LUT_12BIT_G, hwlut.green);
> +					word[1] =
> FIELD_PREP(DISP_GAMMA_LUT_12BIT_B, hwlut.blue);
> +				} else {
> +					word[0] =
> FIELD_PREP(DISP_GAMMA_LUT_10BIT_R, hwlut.red);
> +					word[0] |=
> FIELD_PREP(DISP_GAMMA_LUT_10BIT_G, hwlut.green);
> +					word[0] |=
> FIELD_PREP(DISP_GAMMA_LUT_10BIT_B, hwlut.blue);
> +				}
>  			} else {
>  				diff.red = lut[n].red - lut[n - 1].red;
> -				diff.red =
> drm_color_lut_extract(diff.red, 10);
> +				diff.red =
> drm_color_lut_extract(diff.red, lut_bits);
>  
>  				diff.green = lut[n].green - lut[n -
> 1].green;
> -				diff.green =
> drm_color_lut_extract(diff.green, 10);
> +				diff.green =
> drm_color_lut_extract(diff.green, lut_bits);
>  
>  				diff.blue = lut[n].blue - lut[n -
> 1].blue;
> -				diff.blue =
> drm_color_lut_extract(diff.blue, 10);
> -
> -				word =
> FIELD_PREP(DISP_GAMMA_LUT_10BIT_R, diff.red);
> -				word |=
> FIELD_PREP(DISP_GAMMA_LUT_10BIT_G, diff.green);
> -				word |=
> FIELD_PREP(DISP_GAMMA_LUT_10BIT_B, diff.blue);
> +				diff.blue =
> drm_color_lut_extract(diff.blue, lut_bits);
> +
> +				if (lut_bits == 12) {
> +					word[0] =
> FIELD_PREP(DISP_GAMMA_LUT_12BIT_R, diff.red);
> +					word[0] |=
> FIELD_PREP(DISP_GAMMA_LUT_12BIT_G, diff.green);
> +					word[1] =
> FIELD_PREP(DISP_GAMMA_LUT_12BIT_B, diff.blue);
> +				} else {
> +					word[0] =
> FIELD_PREP(DISP_GAMMA_LUT_10BIT_R, diff.red);
> +					word[0] |=
> FIELD_PREP(DISP_GAMMA_LUT_10BIT_G, diff.green);
> +					word[0] |=
> FIELD_PREP(DISP_GAMMA_LUT_10BIT_B, diff.blue);
> +				}
>  			}
> -			writel(word, lut_base + i * 4);
> +			writel(word[0], lut0_base + i * 4);
> +			if (lut_bits == 12)
> +				writel(word[1], lut1_base + i * 4);
>  		}
>  	}
>  
> @@ -225,11 +268,13 @@ static void mtk_disp_gamma_remove(struct
> platform_device *pdev)
>  static const struct mtk_disp_gamma_data mt8173_gamma_driver_data = {
>  	.has_dither = true,
>  	.lut_bank_size = 512,
> +	.lut_bits = 10,
>  	.lut_size = 512,
>  };
>  
>  static const struct mtk_disp_gamma_data mt8183_gamma_driver_data = {
>  	.lut_bank_size = 512,
> +	.lut_bits = 10,
>  	.lut_diff = true,
>  	.lut_size = 512,
>  };