On 10.03.2017 14:30, Tobias Jakobi wrote:
> The output stage of the mixer uses YCbCr for the internal
> computations, which is the reason that some registers take
> YCbCr related data as input. In particular this applies
> to MXR_BG_COLOR{0,1,2} and MXR_CM_COEFF_{Y,CB,CR}.
>
> Document the formatting of the data which we write to
> these registers.
>
> While at it, unify wording of comments in the register header.
>
> Signed-off-by: Tobias Jakobi <tjakobi@xxxxxxxxxxxxxxxxxxxxx>
Reviewed-by: Andrzej Hajda <a.hajda@xxxxxxxxxxx>
Small nitpick below.
> ---
> Changes in v2:
> - use floating point values as input for the macros, as
> suggested by Andrzej
> - the floating point values have been tuned to exactly match
> the values that are currently used
>
> drivers/gpu/drm/exynos/exynos_mixer.c | 33 +++++++++++++++++++++++++--------
> drivers/gpu/drm/exynos/regs-mixer.h | 7 +++++--
> 2 files changed, 30 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/drm/exynos/exynos_mixer.c b/drivers/gpu/drm/exynos/exynos_mixer.c
> index 41d0c36..9648dd5 100644
> --- a/drivers/gpu/drm/exynos/exynos_mixer.c
> +++ b/drivers/gpu/drm/exynos/exynos_mixer.c
> @@ -45,6 +45,22 @@
> #define MIXER_WIN_NR 3
> #define VP_DEFAULT_WIN 2
>
> +/*
> + * Mixer color space conversion coefficient triplet.
> + * Used for CSC from RGB to YCbCr.
> + * Each coefficient is a 10-bit fixed point number with
> + * sign and no integer part, i.e.
> + * [0:8] = fractional part (representing a value y = x / 2^9)
> + * [9] = sign
> + * Negative values are encoded with two's complement.
> + */
> +#define MXR_CSC_C(x) ((int)((x) * 512.0) & 0x3ff)
> +#define MXR_CSC_CT(a0, a1, a2) \
> + ((MXR_CSC_C(a0) << 20) | (MXR_CSC_C(a1) << 10) | (MXR_CSC_C(a2) << 0))
> +
> +/* YCbCr value, used for mixer background color configuration. */
> +#define MXR_YCBCR_VAL(y, cb, cr) (((y) << 16) | ((cb) << 8) | ((cr) << 0))
> +
> /* The pixelformats that are natively supported by the mixer. */
> #define MXR_FORMAT_RGB565 4
> #define MXR_FORMAT_ARGB1555 5
> @@ -391,13 +407,14 @@ static void mixer_cfg_rgb_fmt(struct mixer_context *ctx, unsigned int height)
> case 1080:
> default:
> val = MXR_CFG_RGB709_16_235;
> + /* Configure the BT.709 CSC matrix for full range RGB. */
> mixer_reg_write(res, MXR_CM_COEFF_Y,
> - (1 << 30) | (94 << 20) | (314 << 10) |
> - (32 << 0));
> + MXR_CSC_CT( 0.1836, 0.6133, 0.0625) |
> + MXR_CM_COEFF_RGB_FULL);
> mixer_reg_write(res, MXR_CM_COEFF_CB,
> - (972 << 20) | (851 << 10) | (225 << 0));
> + MXR_CSC_CT(-0.1016, -0.3379, 0.4395));
> mixer_reg_write(res, MXR_CM_COEFF_CR,
> - (225 << 20) | (820 << 10) | (1004 << 0));
> + MXR_CSC_CT( 0.4395, -0.3985, -0.0391));
It looks like you could use 3-digit coefficients:
0.184, 0.614, 0.063,
-0.102, -0.338, 0.440,
0.440, -0.399, -0.040.
Of course, result is the same.
Regards
Andrzej
> break;
> }
>
> @@ -715,10 +732,10 @@ static void mixer_win_reset(struct mixer_context *ctx)
> /* reset default layer priority */
> mixer_reg_write(res, MXR_LAYER_CFG, 0);
>
> - /* setting background color */
> - mixer_reg_write(res, MXR_BG_COLOR0, 0x008080);
> - mixer_reg_write(res, MXR_BG_COLOR1, 0x008080);
> - mixer_reg_write(res, MXR_BG_COLOR2, 0x008080);
> + /* set all background colors to RGB (0,0,0) */
> + mixer_reg_write(res, MXR_BG_COLOR0, MXR_YCBCR_VAL(0, 128, 128));
> + mixer_reg_write(res, MXR_BG_COLOR1, MXR_YCBCR_VAL(0, 128, 128));
> + mixer_reg_write(res, MXR_BG_COLOR2, MXR_YCBCR_VAL(0, 128, 128));
>
> if (test_bit(MXR_BIT_VP_ENABLED, &ctx->flags)) {
> /* configuration of Video Processor Registers */
> diff --git a/drivers/gpu/drm/exynos/regs-mixer.h b/drivers/gpu/drm/exynos/regs-mixer.h
> index 7f22df5..c311f57 100644
> --- a/drivers/gpu/drm/exynos/regs-mixer.h
> +++ b/drivers/gpu/drm/exynos/regs-mixer.h
> @@ -140,11 +140,11 @@
> #define MXR_INT_EN_VSYNC (1 << 11)
> #define MXR_INT_EN_ALL (0x0f << 8)
>
> -/* bit for MXR_INT_STATUS */
> +/* bits for MXR_INT_STATUS */
> #define MXR_INT_CLEAR_VSYNC (1 << 11)
> #define MXR_INT_STATUS_VSYNC (1 << 0)
>
> -/* bit for MXR_LAYER_CFG */
> +/* bits for MXR_LAYER_CFG */
> #define MXR_LAYER_CFG_GRP1_VAL(x) MXR_MASK_VAL(x, 11, 8)
> #define MXR_LAYER_CFG_GRP1_MASK MXR_LAYER_CFG_GRP1_VAL(~0)
> #define MXR_LAYER_CFG_GRP0_VAL(x) MXR_MASK_VAL(x, 7, 4)
> @@ -152,5 +152,8 @@
> #define MXR_LAYER_CFG_VP_VAL(x) MXR_MASK_VAL(x, 3, 0)
> #define MXR_LAYER_CFG_VP_MASK MXR_LAYER_CFG_VP_VAL(~0)
>
> +/* bits for MXR_CM_COEFF_Y */
> +#define MXR_CM_COEFF_RGB_FULL (1 << 30)
> +
> #endif /* SAMSUNG_REGS_MIXER_H */
>
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