[PATCH 1/2] drm/exynos: dsi: move of_drm_find_bridge call into probe

[Andrzej Hajda]

On 03.07.2017 09:27, Inki Dae wrote:
> This patch moves of_drm_find_bridge call into probe.
>
> It doesn't need to call of_drm_find_bridge function every time
> bind callback is called. It's enough to call this funcation
> at probe one time.
>
> Suggested-by: Inki Dae <inki.dae at samsung.com>
> Signed-off-by: Shuah Khan <shuahkh at osg.samsung.com>
> Signed-off-by: Inki Dae <inki.dae at samsung.com>
> ---
>  drivers/gpu/drm/exynos/exynos_drm_dsi.c | 23 ++++++++++++-----------
>  1 file changed, 12 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_dsi.c b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> index b6a46d9..2412b23 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
> @@ -1661,7 +1661,6 @@ static int exynos_dsi_bind(struct device *dev, struct device *master,
>  	struct drm_encoder *encoder = dev_get_drvdata(dev);
>  	struct exynos_dsi *dsi = encoder_to_dsi(encoder);
>  	struct drm_device *drm_dev = data;
> -	struct drm_bridge *bridge;
>  	int ret;
>  
>  	ret = exynos_drm_crtc_get_pipe_from_type(drm_dev,
> @@ -1685,12 +1684,6 @@ static int exynos_dsi_bind(struct device *dev, struct device *master,
>  		return ret;
>  	}
>  
> -	if (dsi->bridge_node) {
> -		bridge = of_drm_find_bridge(dsi->bridge_node);
> -		if (bridge)
> -			drm_bridge_attach(encoder, bridge, NULL);
> -	}
> -
>  	return mipi_dsi_host_register(&dsi->dsi_host);
>  }
>  
> @@ -1798,6 +1791,18 @@ static int exynos_dsi_probe(struct platform_device *pdev)
>  
>  	platform_set_drvdata(pdev, &dsi->encoder);
>  
> +	if (dsi->bridge_node) {
> +		struct drm_bridge *bridge;
> +
> +		bridge = of_drm_find_bridge(dsi->bridge_node);
> +		if (!bridge)
> +			return -EPROBE_DEFER;
> +
> +		of_node_put(dsi->bridge_node);
> +		drm_bridge_attach(&dsi->encoder, bridge, NULL);
> +	}
> +
> +

One of benefits of componentized drivers is that they do not need to use
probe deferall to wait for other components. There is guarantee that in
bind callback all components are already probed.
This patch looks like step back - it reintroduces probe deferall despite
of existence of better mechanism.
Another issue is that now drm_bridge_attach is called before drm device
creation, and before encoder is registered, even if it works for now, it
does not seem proper, and it can beat us later.
For sure bridge->dev is unitialized, and it can cause warnings.

If you want to put bridge code together it should be put rather into
bind callback.

Regards
Andrzej

>  	pm_runtime_enable(dev);
>  
>  	return component_add(dev, &exynos_dsi_component_ops);
> @@ -1805,10 +1810,6 @@ static int exynos_dsi_probe(struct platform_device *pdev)
>  
>  static int exynos_dsi_remove(struct platform_device *pdev)
>  {
> -	struct exynos_dsi *dsi = platform_get_drvdata(pdev);
> -
> -	of_node_put(dsi->bridge_node);
> -
>  	pm_runtime_disable(&pdev->dev);
>  
>  	component_del(&pdev->dev, &exynos_dsi_component_ops);