Re: [PATCH v2 2/5] drm/exynos: mixer: introduce mixer_layer_blending()

[Inki Dae <inki.dae@samsung.com>]

2015년 11월 23일 01:09에 Tobias Jakobi 이(가) 쓴 글:
> This analyses the current layer configuration (which layers
> are enabled, which have alpha-pixelformat, etc.) and setups
> blending accordingly.
> 
> We currently disable all kinds of blending for the bottom-most
> layer, since configuration of the mixer background is not
> yet exposed.
> Also blending is only enabled when the layer has a pixelformat
> with alpha attached.
> 
> Signed-off-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
> ---
>  drivers/gpu/drm/exynos/exynos_mixer.c | 88 +++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/exynos/regs-mixer.h   |  1 +
>  2 files changed, 89 insertions(+)
> 
> diff --git a/drivers/gpu/drm/exynos/exynos_mixer.c b/drivers/gpu/drm/exynos/exynos_mixer.c
> index 2c1cea3..ec77aad 100644
> --- a/drivers/gpu/drm/exynos/exynos_mixer.c
> +++ b/drivers/gpu/drm/exynos/exynos_mixer.c
> @@ -174,6 +174,21 @@ static const u8 filter_cr_horiz_tap4[] = {
>  	70,	59,	48,	37,	27,	19,	11,	5,
>  };
>  
> +static inline bool is_alpha_format(const struct mixer_context* ctx, unsigned int win)
> +{
> +	const struct drm_plane_state *state = ctx->planes[win].base.state;
> +	const struct drm_framebuffer *fb = state->fb;
> +
> +	switch (fb->pixel_format) {
> +	case DRM_FORMAT_ARGB8888:
> +	case DRM_FORMAT_ARGB1555:
> +	case DRM_FORMAT_ARGB4444:
> +		return true;
> +	default:
> +		return false;
> +	}
> +}
> +
>  static inline u32 vp_reg_read(struct mixer_resources *res, u32 reg_id)
>  {
>  	return readl(res->vp_regs + reg_id);
> @@ -331,6 +346,79 @@ static void mixer_layer_priority(struct mixer_context *ctx)
>  	mixer_reg_write(&ctx->mixer_res, MXR_LAYER_CFG, val);
>  }
>  
> +/* Configure blending for bottom-most layer. */
> +static void mixer_bottom_layer(struct mixer_context *ctx,
> +		const struct layer_cfg *cfg)
> +{
> +	u32 val;
> +	struct mixer_resources *res = &ctx->mixer_res;
> +
> +	if (cfg->index == 2) {
> +		val = 0; /* use defaults for video layer */
> +		mixer_reg_write(res, MXR_VIDEO_CFG, val);
> +	} else {
> +		val = MXR_GRP_CFG_COLOR_KEY_DISABLE; /* no blank key */
> +
> +		/* Don't blend bottom-most layer onto the mixer background. */
> +		mixer_reg_writemask(res, MXR_GRAPHIC_CFG(cfg->index),
> +				    val, MXR_GRP_CFG_MISC_MASK);
> +	}
> +}
> +
> +static void mixer_general_layer(struct mixer_context *ctx,
> +		const struct layer_cfg *cfg)
> +{
> +	u32 val;
> +	struct mixer_resources *res = &ctx->mixer_res;
> +
> +	if (is_alpha_format(ctx, cfg->index)) {
> +		val  = MXR_GRP_CFG_COLOR_KEY_DISABLE; /* no blank key */
> +		val |= MXR_GRP_CFG_BLEND_PRE_MUL;
> +		val |= MXR_GRP_CFG_PIXEL_BLEND_EN; /* blending based on pixel alpha */
> +
> +		/* The video layer never has an alpha pixelformat. */

Looks like above comment isn't related to graphics layer.

> +		mixer_reg_writemask(res, MXR_GRAPHIC_CFG(cfg->index),
> +				    val, MXR_GRP_CFG_MISC_MASK);
> +	} else {
> +		if (cfg->index == 2) {
> +			/*
> +			 * No blending at the moment since the NV12/NV21 pixelformats don't
> +			 * have an alpha channel. However the mixer supports a global alpha
> +			 * value for a layer. Once this functionality is exposed, we can
> +			 * support blending of the video layer through this.
> +			 */
> +			val = 0;
> +			mixer_reg_write(res, MXR_VIDEO_CFG, val);

Above 'if statement' wouldn't be called because cfg->index has always a value less than 2
so it should be removed.

> +		} else {
> +			val = MXR_GRP_CFG_COLOR_KEY_DISABLE;
> +			mixer_reg_writemask(res, MXR_GRAPHIC_CFG(cfg->index),
> +					    val, MXR_GRP_CFG_MISC_MASK);
> +		}
> +	}
> +}
> +
> +static void mixer_layer_blending(struct mixer_context *ctx, unsigned int enable_state)
> +{
> +	unsigned int i, index;
> +	bool bottom_layer = false;
> +
> +	for (i = 0; i < ctx->num_layer; ++i) {
> +		index = ctx->layer_cfg[i].index;
> +
> +		/* Skip layer if it's not enabled. */
> +		if (!(enable_state & (1 << index)))
> +			continue;
> +
> +		/* Bottom layer needs special handling. */
> +		if (bottom_layer) {
> +			mixer_general_layer(ctx, &ctx->layer_cfg[i]);
> +		} else {
> +			mixer_bottom_layer(ctx, &ctx->layer_cfg[i]);
> +			bottom_layer = true;
> +		}

I think above codes could be more cleanned up like below if I understood correctly,

		if (cfg->index == 2) {
			val = 0;
			mixer_reg_write(res, MXR_VIDEO_CFG, val);
		} else {
			mixer_general_layer(ctx, &ctx->layer_cfg[i]);
		}


It'd be better to use a macro - i.e., VIDEO_LAYER - instead of 2.
And how about changing the function name, mixer_general_layer to mixer_grp_layer_set_blending?
Or how about just adding all codes of the function?

Thanks,
Inki Dae

> +	}
> +}
> +
>  static void mixer_vsync_set_update(struct mixer_context *ctx, bool enable)
>  {
>  	struct mixer_resources *res = &ctx->mixer_res;
> diff --git a/drivers/gpu/drm/exynos/regs-mixer.h b/drivers/gpu/drm/exynos/regs-mixer.h
> index ac60260..118872e 100644
> --- a/drivers/gpu/drm/exynos/regs-mixer.h
> +++ b/drivers/gpu/drm/exynos/regs-mixer.h
> @@ -113,6 +113,7 @@
>  #define MXR_GRP_CFG_BLEND_PRE_MUL	(1 << 20)
>  #define MXR_GRP_CFG_WIN_BLEND_EN	(1 << 17)
>  #define MXR_GRP_CFG_PIXEL_BLEND_EN	(1 << 16)
> +#define MXR_GRP_CFG_MISC_MASK		((3 << 16) | (3 << 20))
>  #define MXR_GRP_CFG_FORMAT_VAL(x)	MXR_MASK_VAL(x, 11, 8)
>  #define MXR_GRP_CFG_FORMAT_MASK		MXR_GRP_CFG_FORMAT_VAL(~0)
>  #define MXR_GRP_CFG_ALPHA_VAL(x)	MXR_MASK_VAL(x, 7, 0)
> 
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