Re: [PATCH v8 2/3] drm/mediatek: ovl: Add blend_modes to driver data

["CK Hu (胡俊光)" <ck.hu@mediatek.com>]

Hi, Jason:

On Sun, 2024-09-29 at 00:15 +0800, Jason-JH.Lin wrote:
> OVL_CON_CLRFMT_MAN is a configuration for extending color format
> settings of DISP_REG_OVL_CON(n).
> It will change some of the original color format settings.
> 
> Take the settings of (3 << 12) for example.
> - If OVL_CON_CLRFMT_MAN = 0 means OVL_CON_CLRFMT_RGBA8888.
> - If OVL_CON_CLRFMT_MAN = 1 means OVL_CON_CLRFMT_PARGB8888.
> 
> Since previous SoCs did not support OVL_CON_CLRFMT_MAN, this means
> that the SoC does not support the premultiplied color format.
> It will break the original color format setting of MT8173.
> 
> Therefore, the blend_modes is added to the driver data and then
> mtk_ovl_fmt_convert() will check the blend_modes to see if
> premultiplied supported in current platform.
> If it is not supported, use coverage mode to set it to the supported
> color formats to solve the degradation problem.

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

> 
> Fixes: a3f7f7ef4bfe ("drm/mediatek: Support "Pre-multiplied" blending in OVL")
> Signed-off-by: Jason-JH.Lin <jason-jh.lin@mediatek.com>
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_disp_ovl.c | 34 ++++++++++++++++++++++---
>  1 file changed, 31 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_disp_ovl.c b/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
> index 4a4bc27a67f0..4bfed8a4c14f 100644
> --- a/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
> +++ b/drivers/gpu/drm/mediatek/mtk_disp_ovl.c
> @@ -146,6 +146,7 @@ struct mtk_disp_ovl_data {
>  	bool fmt_rgb565_is_0;
>  	bool smi_id_en;
>  	bool supports_afbc;
> +	const u32 blend_modes;
>  	const u32 *formats;
>  	size_t num_formats;
>  	bool supports_clrfmt_ext;
> @@ -386,9 +387,27 @@ void mtk_ovl_layer_off(struct device *dev, unsigned int idx,
>  		      DISP_REG_OVL_RDMA_CTRL(idx));
>  }
>  
> -static unsigned int ovl_fmt_convert(struct mtk_disp_ovl *ovl, unsigned int fmt,
> -				    unsigned int blend_mode)
> +static unsigned int mtk_ovl_fmt_convert(struct mtk_disp_ovl *ovl,
> +					struct mtk_plane_state *state)
>  {
> +	unsigned int fmt = state->pending.format;
> +	unsigned int blend_mode = DRM_MODE_BLEND_COVERAGE;
> +
> +	/*
> +	 * For the platforms where OVL_CON_CLRFMT_MAN is defined in the hardware data sheet
> +	 * and supports premultiplied color formats, such as OVL_CON_CLRFMT_PARGB8888.
> +	 *
> +	 * Check blend_modes in the driver data to see if premultiplied mode is supported.
> +	 * If not, use coverage mode instead to set it to the supported color formats.
> +	 *
> +	 * Current DRM assumption is that alpha is default premultiplied, so the bitmask of
> +	 * blend_modes must include BIT(DRM_MODE_BLEND_PREMULTI). Otherwise, mtk_plane_init()
> +	 * will get an error return from drm_plane_create_blend_mode_property() and
> +	 * state->base.pixel_blend_mode should not be used.
> +	 */
> +	if (ovl->data->blend_modes & BIT(DRM_MODE_BLEND_PREMULTI))
> +		blend_mode = state->base.pixel_blend_mode;
> +
>  	switch (fmt) {
>  	default:
>  	case DRM_FORMAT_RGB565:
> @@ -466,7 +485,7 @@ void mtk_ovl_layer_config(struct device *dev, unsigned int idx,
>  		return;
>  	}
>  
> -	con = ovl_fmt_convert(ovl, fmt, blend_mode);
> +	con = mtk_ovl_fmt_convert(ovl, state);
>  	if (state->base.fb) {
>  		con |= OVL_CON_AEN;
>  		con |= state->base.alpha & OVL_CON_ALPHA;
> @@ -658,6 +677,9 @@ static const struct mtk_disp_ovl_data mt8192_ovl_driver_data = {
>  	.layer_nr = 4,
>  	.fmt_rgb565_is_0 = true,
>  	.smi_id_en = true,
> +	.blend_modes = BIT(DRM_MODE_BLEND_PREMULTI) |
> +		       BIT(DRM_MODE_BLEND_COVERAGE) |
> +		       BIT(DRM_MODE_BLEND_PIXEL_NONE),
>  	.formats = mt8173_formats,
>  	.num_formats = ARRAY_SIZE(mt8173_formats),
>  };
> @@ -668,6 +690,9 @@ static const struct mtk_disp_ovl_data mt8192_ovl_2l_driver_data = {
>  	.layer_nr = 2,
>  	.fmt_rgb565_is_0 = true,
>  	.smi_id_en = true,
> +	.blend_modes = BIT(DRM_MODE_BLEND_PREMULTI) |
> +		       BIT(DRM_MODE_BLEND_COVERAGE) |
> +		       BIT(DRM_MODE_BLEND_PIXEL_NONE),
>  	.formats = mt8173_formats,
>  	.num_formats = ARRAY_SIZE(mt8173_formats),
>  };
> @@ -679,6 +704,9 @@ static const struct mtk_disp_ovl_data mt8195_ovl_driver_data = {
>  	.fmt_rgb565_is_0 = true,
>  	.smi_id_en = true,
>  	.supports_afbc = true,
> +	.blend_modes = BIT(DRM_MODE_BLEND_PREMULTI) |
> +		       BIT(DRM_MODE_BLEND_COVERAGE) |
> +		       BIT(DRM_MODE_BLEND_PIXEL_NONE),
>  	.formats = mt8195_formats,
>  	.num_formats = ARRAY_SIZE(mt8195_formats),
>  	.supports_clrfmt_ext = true,