Re: [PATCH RESEND v6 09/11] drm/mediatek: gamma: Add support for 12-bit LUT and MT8195

[Alexandre Mergnat <amergnat@baylibre.com>]

Hi Angelo !

On 27/07/2023 11:46, AngeloGioacchino Del Regno wrote:
> Add support for 12-bit gamma lookup tables and introduce the first
> user for it: MT8195.
> While at it, also reorder the variables in mtk_gamma_set_common()
> and rename `lut_base` to `lut0_base` to improve readability.
> 
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
> Reviewed-by: Jason-JH.Lin <jason-jh.lin@mediatek.com>
> ---
>   drivers/gpu/drm/mediatek/mtk_disp_gamma.c | 61 ++++++++++++++++++-----
>   1 file changed, 48 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_disp_gamma.c b/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
> index f1a0b18b6c1a..e0e2d2bdbf59 100644
> --- a/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
> +++ b/drivers/gpu/drm/mediatek/mtk_disp_gamma.c
> @@ -27,12 +27,20 @@
>   #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

Is this offset generic to all MTK SoC which support this driver ?

>   
> +/* 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 */

As I understood from the application processor registers (v0.4), R/G are 
in LUT, B is in LUT1 for 10bit and 12bit for MT8195. Can you check 
please to be sure ?

> +#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)
> +
>   #define LUT_10BIT_MASK				0x03ff
>   #define LUT_BITS_DEFAULT			10
>   #define LUT_SIZE_DEFAULT			512
> @@ -83,14 +91,15 @@ unsigned int mtk_gamma_get_lut_size(struct device *dev)
>   void mtk_gamma_set_common(struct device *dev, void __iomem *regs, struct drm_crtc_state *state)
>   {
>   	struct mtk_disp_gamma *gamma = dev_get_drvdata(dev);
> -	unsigned int i;
> +	void __iomem *lut0_base = regs + DISP_GAMMA_LUT;
> +	void __iomem *lut1_base = regs + DISP_GAMMA_LUT1;
> +	u32 cfg_val, data_mode, lbank_val, word[2];
> +	int cur_bank, num_lut_banks;
> +	u16 lut_bank_size, lut_size;
>   	struct drm_color_lut *lut;
> -	void __iomem *lut_base;
> +	unsigned int i;
>   	bool lut_diff;
> -	u16 lut_bank_size, lut_size;
>   	u8 lut_bits;
> -	u32 cfg_val, lbank_val, word;
> -	int cur_bank, num_lut_banks;
>   
>   	/* If there's no gamma lut there's nothing to do here. */
>   	if (!state->gamma_lut)
> @@ -110,14 +119,17 @@ void mtk_gamma_set_common(struct device *dev, void __iomem *regs, struct drm_crt
>   	num_lut_banks = lut_size / lut_bank_size;
>   
>   	cfg_val = readl(regs + DISP_GAMMA_CFG);
> -	lut_base = 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, regs + DISP_GAMMA_BANK);
>   		}
>   
> @@ -130,9 +142,15 @@ void mtk_gamma_set_common(struct device *dev, void __iomem *regs, struct drm_crt
>   			hwlut.blue = drm_color_lut_extract(lut[n].blue, lut_bits);
>   
>   			if (!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, lut_bits);
> @@ -143,11 +161,19 @@ void mtk_gamma_set_common(struct device *dev, void __iomem *regs, struct drm_crt
>   				diff.blue = lut[n].blue - lut[n - 1].blue;
>   				diff.blue = drm_color_lut_extract(diff.blue, lut_bits);
>   
> -				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);
> +				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));

ditto

>   		}
>   	}
>   
> @@ -271,11 +297,20 @@ static const struct mtk_disp_gamma_data mt8183_gamma_driver_data = {
>   	.lut_size = 512,
>   };
>   
> +static const struct mtk_disp_gamma_data mt8195_gamma_driver_data = {
> +	.lut_bank_size = 256,
> +	.lut_bits = 12,

If I'm right, ".lut_bits = 10" will not work properly.

> +	.lut_diff = true,
> +	.lut_size = 1024,
> +};
> +
>   static const struct of_device_id mtk_disp_gamma_driver_dt_match[] = {
>   	{ .compatible = "mediatek,mt8173-disp-gamma",
>   	  .data = &mt8173_gamma_driver_data},
>   	{ .compatible = "mediatek,mt8183-disp-gamma",
>   	  .data = &mt8183_gamma_driver_data},
> +	{ .compatible = "mediatek,mt8195-disp-gamma",
> +	  .data = &mt8195_gamma_driver_data},
>   	{},
>   };
>   MODULE_DEVICE_TABLE(of, mtk_disp_gamma_driver_dt_match);

-- 
Regards,
Alexandre