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

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Message-ID: <YaWZgkL6phajVdvy@pendragon.ideasonboard.com>
Date:   Tue, 30 Nov 2021 05:24:50 +0200
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Kieran Bingham <kieran.bingham+renesas@...asonboard.com>
Cc:     linux-renesas-soc@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/4] drm: rcar-du: mipi-dsi: Support bridge probe ordering

Hi Kieran,

Thank you for the patch.

On Fri, Nov 26, 2021 at 10:15:18AM +0000, Kieran Bingham wrote:
> The bridge probe ordering for DSI devices has been clarified and further
> documented in

In what ? :-)

> 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>

Will you send a new version of this patch with Biju's comments taken
into account ? I've already applied 1/4 to 3/4 to my tree, so there's no
need to repost them.

> ---
>  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;
> +	}
> +
> +	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 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;

-- 
Regards,

Laurent Pinchart