Subject: Re: [RESEND PATCH 2/3] drm/mediatek: mtk_dpi: Convert to bridge driver

From: Boris Brezillon <[email-masked]>
Date: Wed, 1 Jul 2020 13:51:53 +0200

On Mon, 18 May 2020 19:39:08 +0200
Enric Balletbo i Serra <[email-masked]> wrote:

> Convert mtk_dpi to a bridge driver with built-in encoder support for
> compatibility with existing component drivers.
> 
> Signed-off-by: Enric Balletbo i Serra <[email-masked]>
> Reviewed-by: Chun-Kuang Hu <[email-masked]>
> ---
> 
>  drivers/gpu/drm/mediatek/mtk_dpi.c | 66 +++++++++++++++---------------
>  1 file changed, 34 insertions(+), 32 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_dpi.c b/drivers/gpu/drm/mediatek/mtk_dpi.c
> index 7112125dc3d1..baad198c69eb 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dpi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dpi.c
> @@ -61,6 +61,7 @@ enum mtk_dpi_out_color_format {
>  struct mtk_dpi {
>  	struct mtk_ddp_comp ddp_comp;
>  	struct drm_encoder encoder;
> +	struct drm_bridge bridge;
>  	struct drm_bridge *next_bridge;
>  	void __iomem *regs;
>  	struct device *dev;
> @@ -77,9 +78,9 @@ struct mtk_dpi {
>  	int refcount;
>  };
>  
> -static inline struct mtk_dpi *mtk_dpi_from_encoder(struct drm_encoder *e)
> +static inline struct mtk_dpi *bridge_to_dpi(struct drm_bridge *b)
>  {
> -	return container_of(e, struct mtk_dpi, encoder);
> +	return container_of(b, struct mtk_dpi, bridge);
>  }
>  
>  enum mtk_dpi_polarity {
> @@ -518,50 +519,44 @@ static const struct drm_encoder_funcs mtk_dpi_encoder_funcs = {
>  	.destroy = mtk_dpi_encoder_destroy,
>  };
>  
> -static bool mtk_dpi_encoder_mode_fixup(struct drm_encoder *encoder,
> -				       const struct drm_display_mode *mode,
> -				       struct drm_display_mode *adjusted_mode)
> +static int mtk_dpi_bridge_attach(struct drm_bridge *bridge,
> +				 enum drm_bridge_attach_flags flags)
>  {
> -	return true;
> +	struct mtk_dpi *dpi = bridge_to_dpi(bridge);
> +
> +	return drm_bridge_attach(bridge->encoder, dpi->next_bridge,
> +				 &dpi->bridge, flags);
>  }
>  
> -static void mtk_dpi_encoder_mode_set(struct drm_encoder *encoder,
> -				     struct drm_display_mode *mode,
> -				     struct drm_display_mode *adjusted_mode)
> +static void mtk_dpi_bridge_mode_set(struct drm_bridge *bridge,
> +				const struct drm_display_mode *mode,
> +				const struct drm_display_mode *adjusted_mode)
>  {
> -	struct mtk_dpi *dpi = mtk_dpi_from_encoder(encoder);
> +	struct mtk_dpi *dpi = bridge_to_dpi(bridge);
>  
>  	drm_mode_copy(&dpi->mode, adjusted_mode);
>  }
>  
> -static void mtk_dpi_encoder_disable(struct drm_encoder *encoder)
> +static void mtk_dpi_bridge_disable(struct drm_bridge *bridge)
>  {
> -	struct mtk_dpi *dpi = mtk_dpi_from_encoder(encoder);
> +	struct mtk_dpi *dpi = bridge_to_dpi(bridge);
>  
>  	mtk_dpi_power_off(dpi);
>  }
>  
> -static void mtk_dpi_encoder_enable(struct drm_encoder *encoder)
> +static void mtk_dpi_bridge_enable(struct drm_bridge *bridge)
>  {
> -	struct mtk_dpi *dpi = mtk_dpi_from_encoder(encoder);
> +	struct mtk_dpi *dpi = bridge_to_dpi(bridge);
>  
>  	mtk_dpi_power_on(dpi);
>  	mtk_dpi_set_display_mode(dpi, &dpi->mode);
>  }
>  
> -static int mtk_dpi_atomic_check(struct drm_encoder *encoder,
> -				struct drm_crtc_state *crtc_state,
> -				struct drm_connector_state *conn_state)
> -{
> -	return 0;
> -}
> -
> -static const struct drm_encoder_helper_funcs mtk_dpi_encoder_helper_funcs = {
> -	.mode_fixup = mtk_dpi_encoder_mode_fixup,
> -	.mode_set = mtk_dpi_encoder_mode_set,
> -	.disable = mtk_dpi_encoder_disable,
> -	.enable = mtk_dpi_encoder_enable,
> -	.atomic_check = mtk_dpi_atomic_check,
> +static const struct drm_bridge_funcs mtk_dpi_bridge_funcs = {
> +	.attach = mtk_dpi_bridge_attach,
> +	.mode_set = mtk_dpi_bridge_mode_set,
> +	.disable = mtk_dpi_bridge_disable,
> +	.enable = mtk_dpi_bridge_enable,
>  };
>  
>  static void mtk_dpi_start(struct mtk_ddp_comp *comp)
> @@ -602,16 +597,13 @@ static int mtk_dpi_bind(struct device *dev, struct device *master, void *data)
>  		dev_err(dev, "Failed to initialize decoder: %d\n", ret);
>  		goto err_unregister;
>  	}
> -	drm_encoder_helper_add(&dpi->encoder, &mtk_dpi_encoder_helper_funcs);
>  
>  	/* Currently DPI0 is fixed to be driven by OVL1 */
>  	dpi->encoder.possible_crtcs = BIT(1);
>  
> -	ret = drm_bridge_attach(&dpi->encoder, dpi->next_bridge, NULL, 0);
> -	if (ret) {
> -		dev_err(dev, "Failed to attach bridge: %d\n", ret);

Any reason your decided to drop this error message? If there's one,
this should probably happen in a separate patch.

> +	ret = drm_bridge_attach(&dpi->encoder, &dpi->bridge, NULL, 0);
> +	if (ret)
>  		goto err_cleanup;
> -	}
>  
>  	dpi->bit_num = MTK_DPI_OUT_BIT_NUM_8BITS;
>  	dpi->channel_swap = MTK_DPI_OUT_CHANNEL_SWAP_RGB;
> @@ -768,8 +760,15 @@ static int mtk_dpi_probe(struct platform_device *pdev)
>  
>  	platform_set_drvdata(pdev, dpi);
>  
> +	dpi->bridge.funcs = &mtk_dpi_bridge_funcs;
> +	dpi->bridge.of_node = dev->of_node;
> +	dpi->bridge.type = DRM_MODE_CONNECTOR_DPI;
> +
> +	drm_bridge_add(&dpi->bridge);

I wonder if it's really useful to add the bridge when it's private (you
don't want this bridge to be added to external bridge chains).

> +
>  	ret = component_add(dev, &mtk_dpi_component_ops);
>  	if (ret) {
> +		drm_bridge_remove(&dpi->bridge);
>  		dev_err(dev, "Failed to add component: %d\n", ret);
>  		return ret;
>  	}
> @@ -779,7 +778,10 @@ static int mtk_dpi_probe(struct platform_device *pdev)
>  
>  static int mtk_dpi_remove(struct platform_device *pdev)
>  {
> +	struct mtk_dpi *dpi = platform_get_drvdata(pdev);
> +
>  	component_del(&pdev->dev, &mtk_dpi_component_ops);
> +	drm_bridge_remove(&dpi->bridge);
>  
>  	return 0;
>  }

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