Re: [PATCH v3 1/3] drm: Add callbacks for late registering

[Daniel Vetter <daniel@ffwll.ch>]

On Tue, Jun 21, 2016 at 03:09:38PM +0200, Benjamin Gaignard wrote:
> Like what has been done for connectors add callbacks on encoder,
> crtc and plane to let driver do actions after drm device registration.
> 
> Correspondingly, add callbacks called before unregister drm device.
> 
> version 2:
> add drm_modeset_register_all() and drm_modeset_unregister_all()
> to centralize all calls
> 
> version 3:
> in error case unwind registers in drm_modeset_register_all
> fix uninitialed return value
> inverse order of unregistration in drm_modeset_unregister_all
> 
> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
> ---
>  drivers/gpu/drm/drm_crtc.c | 132 +++++++++++++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/drm_drv.c  |   4 +-
>  include/drm/drm_crtc.h     |  79 +++++++++++++++++++++++++++
>  3 files changed, 213 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
> index e7c862b..c078bc4 100644
> --- a/drivers/gpu/drm/drm_crtc.c
> +++ b/drivers/gpu/drm/drm_crtc.c
> @@ -608,6 +608,31 @@ static unsigned int drm_num_crtcs(struct drm_device *dev)
>  	return num;
>  }
>  
> +static int drm_crtc_register_all(struct drm_device *dev)
> +{
> +	struct drm_crtc *crtc;
> +	int ret = 0;
> +
> +	drm_for_each_crtc(crtc, dev) {
> +		if (crtc->funcs->late_register)
> +			ret = crtc->funcs->late_register(crtc);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static void drm_crtc_unregister_all(struct drm_device *dev)
> +{
> +	struct drm_crtc *crtc;
> +
> +	drm_for_each_crtc(crtc, dev) {
> +		if (crtc->funcs->early_unregister)
> +			crtc->funcs->early_unregister(crtc);
> +	}
> +}
> +
>  /**
>   * drm_crtc_init_with_planes - Initialise a new CRTC object with
>   *    specified primary and cursor planes.
> @@ -1102,6 +1127,31 @@ void drm_connector_unregister_all(struct drm_device *dev)
>  }
>  EXPORT_SYMBOL(drm_connector_unregister_all);
>  
> +static int drm_encoder_register_all(struct drm_device *dev)
> +{
> +	struct drm_encoder *encoder;
> +	int ret = 0;
> +
> +	drm_for_each_encoder(encoder, dev) {
> +		if (encoder->funcs->late_register)
> +			ret = encoder->funcs->late_register(encoder);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static void drm_encoder_unregister_all(struct drm_device *dev)
> +{
> +	struct drm_encoder *encoder;
> +
> +	drm_for_each_encoder(encoder, dev) {
> +		if (encoder->funcs->early_unregister)
> +			encoder->funcs->early_unregister(encoder);
> +	}
> +}
> +
>  /**
>   * drm_encoder_init - Init a preallocated encoder
>   * @dev: drm device
> @@ -1290,6 +1340,31 @@ int drm_universal_plane_init(struct drm_device *dev, struct drm_plane *plane,
>  }
>  EXPORT_SYMBOL(drm_universal_plane_init);
>  
> +static int drm_plane_register_all(struct drm_device *dev)
> +{
> +	struct drm_plane *plane;
> +	int ret = 0;
> +
> +	drm_for_each_plane(plane, dev) {
> +		if (plane->funcs->late_register)
> +			ret = plane->funcs->late_register(plane);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static void drm_plane_unregister_all(struct drm_device *dev)
> +{
> +	struct drm_plane *plane;
> +
> +	drm_for_each_plane(plane, dev) {
> +		if (plane->funcs->early_unregister)
> +			plane->funcs->early_unregister(plane);
> +	}
> +}
> +
>  /**
>   * drm_plane_init - Initialize a legacy plane
>   * @dev: DRM device
> @@ -1412,6 +1487,63 @@ void drm_plane_force_disable(struct drm_plane *plane)
>  }
>  EXPORT_SYMBOL(drm_plane_force_disable);
>  
> +/**
> + * drm_modeset_register_all - do late registration
> + * @dev: drm device
> + *
> + * This function call late_register callback for all planes,
> + * crcts, encoders and connectors
> + *
> + * Returns:
> + * Zero on success, erro code on failure
> + */

We don't document drm-internal functions, it just confuses the docs (which
are aimed at driver writers). Since the comment doesn't explain much of
what the code does, please remove. Same for unregister below.

> +int drm_modeset_register_all(struct drm_device *dev)
> +{
> +	int ret;
> +
> +	ret = drm_plane_register_all(dev);
> +	if (ret)
> +		goto err_plane;
> +
> +	ret = drm_crtc_register_all(dev);
> +	if  (ret)
> +		goto err_crtc;
> +
> +	ret = drm_encoder_register_all(dev);
> +	if (ret)
> +		goto err_encoder;
> +
> +	ret = drm_connector_register_all(dev);
> +	if (ret)
> +		goto err_connector;
> +
> +	return 0;
> +
> +err_connector:
> +	drm_encoder_unregister_all(dev);
> +err_encoder:
> +	drm_crtc_unregister_all(dev);
> +err_crtc:
> +	drm_plane_unregister_all(dev);
> +err_plane:
> +	return ret;
> +}
> +
> +/**
> + * drm_modeset_unregister_all - do early unregistration
> + * @dev: drm device
> + *
> + * This function call early_unregister callbacks for all
> + * connectors, encoders, crtcs and planes
> + */
> +void drm_modeset_unregister_all(struct drm_device *dev)
> +{
> +	drm_connector_unregister_all(dev);
> +	drm_encoder_unregister_all(dev);
> +	drm_crtc_unregister_all(dev);
> +	drm_plane_unregister_all(dev);
> +}
> +
>  static int drm_mode_create_standard_properties(struct drm_device *dev)
>  {
>  	struct drm_property *prop;
> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
> index c7101c0..53eadca 100644
> --- a/drivers/gpu/drm/drm_drv.c
> +++ b/drivers/gpu/drm/drm_drv.c
> @@ -688,7 +688,7 @@ int drm_dev_register(struct drm_device *dev, unsigned long flags)
>  	}
>  
>  	if (drm_core_check_feature(dev, DRIVER_MODESET))
> -		drm_connector_register_all(dev);
> +		drm_modeset_register_all(dev);
>  
>  	ret = 0;
>  	goto out_unlock;
> @@ -721,7 +721,7 @@ void drm_dev_unregister(struct drm_device *dev)
>  	drm_lastclose(dev);
>  
>  	if (drm_core_check_feature(dev, DRIVER_MODESET))
> -		drm_connector_unregister_all(dev);
> +		drm_modeset_unregister_all(dev);
>  
>  	if (dev->driver->unload)
>  		dev->driver->unload(dev);
> diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
> index c273497..d0f2256b 100644
> --- a/include/drm/drm_crtc.h
> +++ b/include/drm/drm_crtc.h
> @@ -704,6 +704,32 @@ struct drm_crtc_funcs {
>  				   const struct drm_crtc_state *state,
>  				   struct drm_property *property,
>  				   uint64_t *val);
> +
> +	/**
> +	 * @late_register:
> +	 *
> +	 * This optional hook can be used to register additional userspace
> +	 * interfaces attached to the crtc like debugfs interfaces.
> +	 * It is called late in the driver load sequence from drm_dev_register().
> +	 * Everything added from this callback should be unregistered in
> +	 * the early_unregister callback.
> +	 *
> +	 * Returns:
> +	 *
> +	 * 0 on success, or a negative error code on failure.
> +	 */
> +	int (*late_register)(struct drm_crtc *crtc);
> +
> +	/**
> +	 * @early_unregister:
> +	 *
> +	 * This optional hook should be used to unregister the additional
> +	 * userspace interfaces attached to the crtc from
> +	 * late_unregister(). It is called from drm_dev_unregister(),
> +	 * early in the driver unload sequence to disable userspace access
> +	 * before data structures are torndown.
> +	 */
> +	void (*early_unregister)(struct drm_crtc *crtc);
>  };
>  
>  /**
> @@ -1127,6 +1153,32 @@ struct drm_encoder_funcs {
>  	 * hotplugged in DRM.
>  	 */
>  	void (*destroy)(struct drm_encoder *encoder);
> +
> +	/**
> +	 * @late_register:
> +	 *
> +	 * This optional hook can be used to register additional userspace
> +	 * interfaces attached to the encoder like debugfs interfaces.
> +	 * It is called late in the driver load sequence from drm_dev_register().
> +	 * Everything added from this callback should be unregistered in
> +	 * the early_unregister callback.
> +	 *
> +	 * Returns:
> +	 *
> +	 * 0 on success, or a negative error code on failure.
> +	 */
> +	int (*late_register)(struct drm_encoder *encoder);
> +
> +	/**
> +	 * @early_unregister:
> +	 *
> +	 * This optional hook should be used to unregister the additional
> +	 * userspace interfaces attached to the encoder from
> +	 * late_unregister(). It is called from drm_dev_unregister(),
> +	 * early in the driver unload sequence to disable userspace access
> +	 * before data structures are torndown.
> +	 */
> +	void (*early_unregister)(struct drm_encoder *encoder);
>  };
>  
>  #define DRM_CONNECTOR_MAX_ENCODER 3
> @@ -1570,6 +1622,31 @@ struct drm_plane_funcs {
>  				   const struct drm_plane_state *state,
>  				   struct drm_property *property,
>  				   uint64_t *val);
> +	/**
> +	 * @late_register:
> +	 *
> +	 * This optional hook can be used to register additional userspace
> +	 * interfaces attached to the plane like debugfs interfaces.
> +	 * It is called late in the driver load sequence from drm_dev_register().
> +	 * Everything added from this callback should be unregistered in
> +	 * the early_unregister callback.
> +	 *
> +	 * Returns:
> +	 *
> +	 * 0 on success, or a negative error code on failure.
> +	 */
> +	int (*late_register)(struct drm_plane *plane);
> +
> +	/**
> +	 * @early_unregister:
> +	 *
> +	 * This optional hook should be used to unregister the additional
> +	 * userspace interfaces attached to the plane from
> +	 * late_unregister(). It is called from drm_dev_unregister(),
> +	 * early in the driver unload sequence to disable userspace access
> +	 * before data structures are torndown.
> +	 */
> +	void (*early_unregister)(struct drm_plane *plane);
>  };
>  
>  enum drm_plane_type {
> @@ -2514,6 +2591,8 @@ static inline unsigned drm_connector_index(struct drm_connector *connector)
>  /* helpers to {un}register all connectors from sysfs for device */
>  extern int drm_connector_register_all(struct drm_device *dev);
>  extern void drm_connector_unregister_all(struct drm_device *dev);
> +int drm_modeset_register_all(struct drm_device *dev);
> +void drm_modeset_unregister_all(struct drm_device *dev);

Please move these to drm_crtc_internal.h, it's not part of the driver api.
-Daniel

>  
>  extern int drm_bridge_add(struct drm_bridge *bridge);
>  extern void drm_bridge_remove(struct drm_bridge *bridge);
> -- 
> 1.9.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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