[alsa-devel] [PATCH v5 1/7] drm: sunxi: Add a basic DRM driver for Allwinner DE2

[Daniel Vetter]

On Fri, Oct 21, 2016 at 09:26:18AM +0200, Jean-Francois Moine wrote:
> +static int de2_drm_bind(struct device *dev)
> +{
> +	struct drm_device *drm;
> +	struct priv *priv;
> +	int ret;
> +
> +	drm = drm_dev_alloc(&de2_drm_driver, dev);
> +	if (!drm)
> +		return -ENOMEM;
> +
> +	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
> +	if (!priv) {
> +		dev_err(dev, "failed to allocate private area\n");
> +		ret = -ENOMEM;
> +		goto out1;
> +	}
> +
> +	dev_set_drvdata(dev, drm);
> +	drm->dev_private = priv;
> +
> +	drm_mode_config_init(drm);
> +	drm->mode_config.min_width = 32;	/* needed for cursor */
> +	drm->mode_config.min_height = 32;
> +	drm->mode_config.max_width = 1920;
> +	drm->mode_config.max_height = 1080;
> +	drm->mode_config.funcs = &de2_mode_config_funcs;
> +
> +	drm->irq_enabled = true;
> +
> +	/* initialize the display engine */
> +	priv->soc_type = (int) of_match_device(de2_drm_of_match, dev)->data;
> +	ret = de2_de_init(priv, dev);
> +	if (ret)
> +		goto out2;
> +
> +	/* start the subdevices */
> +	ret = component_bind_all(dev, drm);
> +	if (ret < 0)
> +		goto out2;
> +
> +	ret = drm_dev_register(drm, 0);

This needs to be the very last step in your driver load sequence.
Kerneldoc explains why. Similar, but inverted for unloading:
drm_dev_unregister is the very first thing you must call.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch