linux-kernel - RE: [PATCH 4/4] drm: rcar-du: mipi-dsi: Support bridge probe ordering

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Message-ID: <OS0PR01MB5922819388EAA6973EDCD3D386639@OS0PR01MB5922.jpnprd01.prod.outlook.com>
Date:   Fri, 26 Nov 2021 10:51:48 +0000
From:   Biju Das <biju.das.jz@...renesas.com>
To:     Kieran Bingham <kieran.bingham+renesas@...asonboard.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        "linux-renesas-soc@...r.kernel.org" 
        <linux-renesas-soc@...r.kernel.org>
CC:     "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 4/4] drm: rcar-du: mipi-dsi: Support bridge probe ordering

Hi Kieran,

Thanks for the patch.

> Subject: [PATCH 4/4] drm: rcar-du: mipi-dsi: Support bridge probe ordering
> 
> The bridge probe ordering for DSI devices has been clarified and further
> documented in
> 
> To support connecting with the SN65DSI86 device after commit c3b75d4734cb
> ("drm/bridge: sn65dsi86: Register and attach our DSI device at probe"),
> update to the new probe ordering to remove a perpetual -EPROBE_DEFER loop
> between the two devices.
> 
> Signed-off-by: Kieran Bingham <kieran.bingham+renesas@...asonboard.com>
> ---
>  drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c | 48 +++++++++++++------------
>  1 file changed, 26 insertions(+), 22 deletions(-)
> 
> diff --git a/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c
> b/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c
> index 833f4480bdf3..f783bacee8da 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c
> @@ -639,6 +639,8 @@ static int rcar_mipi_dsi_host_attach(struct
> mipi_dsi_host *host,
>  					struct mipi_dsi_device *device)
>  {
>  	struct rcar_mipi_dsi *dsi = host_to_rcar_mipi_dsi(host);
> +	struct drm_panel *panel;
> +	int ret;
> 
>  	if (device->lanes > dsi->num_data_lanes)
>  		return -EINVAL;
> @@ -646,12 +648,36 @@ static int rcar_mipi_dsi_host_attach(struct
> mipi_dsi_host *host,
>  	dsi->lanes = device->lanes;
>  	dsi->format = device->format;
> 
> +	ret = drm_of_find_panel_or_bridge(dsi->dev->of_node, 1, 0, &panel,
> +					  &dsi->next_bridge);
> +	if (ret) {
> +		dev_err_probe(dsi->dev, ret, "could not find next bridge\n");
> +		return ret;

This can merged with previous line. return dev_err_probe(dsi->dev, ret, "could not find next bridge\n");
> +	}
> +
> +	if (!dsi->next_bridge) {
> +		dsi->next_bridge = devm_drm_panel_bridge_add(dsi->dev, panel);
> +		if (IS_ERR(dsi->next_bridge)) {
> +			dev_err(dsi->dev, "failed to create panel bridge\n");
> +			return PTR_ERR(dsi->next_bridge);

Why not return dev_err_probe??

Cheers,
Biju

> +		}
> +	}
> +
> +	/* Initialize the DRM bridge. */
> +	dsi->bridge.funcs = &rcar_mipi_dsi_bridge_ops;
> +	dsi->bridge.of_node = dsi->dev->of_node;
> +	drm_bridge_add(&dsi->bridge);
> +
>  	return 0;
>  }
> 
>  static int rcar_mipi_dsi_host_detach(struct mipi_dsi_host *host,
>  					struct mipi_dsi_device *device)
>  {
> +	struct rcar_mipi_dsi *dsi = host_to_rcar_mipi_dsi(host);
> +
> +	drm_bridge_remove(&dsi->bridge);
> +
>  	return 0;
>  }
> 
> @@ -766,21 +792,6 @@ static int rcar_mipi_dsi_probe(struct platform_device
> *pdev)
>  		return PTR_ERR(dsi->rstc);
>  	}
> 
> -	ret = drm_of_find_panel_or_bridge(dsi->dev->of_node, 1, 0, &panel,
> -					  &dsi->next_bridge);
> -	if (ret) {
> -		dev_err_probe(dsi->dev, ret, "could not find next bridge\n");
> -		return ret;
> -	}
> -
> -	if (!dsi->next_bridge) {
> -		dsi->next_bridge = devm_drm_panel_bridge_add(dsi->dev, panel);
> -		if (IS_ERR(dsi->next_bridge)) {
> -			dev_err(dsi->dev, "failed to create panel bridge\n");
> -			return PTR_ERR(dsi->next_bridge);
> -		}
> -	}
> -
>  	/* Initialize the DSI host. */
>  	dsi->host.dev = dsi->dev;
>  	dsi->host.ops = &rcar_mipi_dsi_host_ops; @@ -788,11 +799,6 @@ static
> int rcar_mipi_dsi_probe(struct platform_device *pdev)
>  	if (ret < 0)
>  		return ret;
> 
> -	/* Initialize the DRM bridge. */
> -	dsi->bridge.funcs = &rcar_mipi_dsi_bridge_ops;
> -	dsi->bridge.of_node = dsi->dev->of_node;
> -	drm_bridge_add(&dsi->bridge);
> -
>  	return 0;
>  }
> 
> @@ -800,8 +806,6 @@ static int rcar_mipi_dsi_remove(struct platform_device
> *pdev)  {
>  	struct rcar_mipi_dsi *dsi = platform_get_drvdata(pdev);
> 
> -	drm_bridge_remove(&dsi->bridge);
> -
>  	mipi_dsi_host_unregister(&dsi->host);
> 
>  	return 0;
> --
> 2.30.2