Re: [PATCH 2/4] components: multiple components for a device

[Russell King - ARM Linux admin]

On Fri, Feb 08, 2019 at 12:27:57AM +0100, Daniel Vetter wrote:
> Component framework is extended to support multiple components for
> a struct device. These will be matched with different masters based on
> its sub component value.
> 
> We are introducing this, as I915 needs two different components
> with different subcomponent value, which will be matched to two
> different component masters(Audio and HDCP) based on the subcomponent
> values.
> 
> v2: Add documenation.
> 
> v3: Rebase on top of updated documenation.
> 
> v4: Review from Rafael:
> - Remove redundant "This" from kerneldoc (also in the previous patch)
> - Streamline the logic in find_component() a bit.
> 
> Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxx> (v1 code)
> Signed-off-by: Ramalingam C <ramalingam.c@xxxxxxxxx> (v1 commit message)
> Cc: Ramalingam C <ramalingam.c@xxxxxxxxx>
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Cc: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
> Cc: Rafael J. Wysocki <rafael@xxxxxxxxxx>
> Cc: Jaroslav Kysela <perex@xxxxxxxx>
> Cc: Takashi Iwai <tiwai@xxxxxxxx>
> Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
> Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
> Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
> ---
>  drivers/base/component.c  | 158 +++++++++++++++++++++++++++++---------
>  include/linux/component.h |  10 ++-
>  2 files changed, 129 insertions(+), 39 deletions(-)
> 
> diff --git a/drivers/base/component.c b/drivers/base/component.c
> index 1624c2a892a5..7dbc41cccd58 100644
> --- a/drivers/base/component.c
> +++ b/drivers/base/component.c
> @@ -47,6 +47,7 @@ struct component;
>  struct component_match_array {
>  	void *data;
>  	int (*compare)(struct device *, void *);
> +	int (*compare_typed)(struct device *, int, void *);
>  	void (*release)(struct device *, void *);
>  	struct component *component;
>  	bool duplicate;
> @@ -74,6 +75,7 @@ struct component {
>  	bool bound;
>  
>  	const struct component_ops *ops;
> +	int subcomponent;
>  	struct device *dev;
>  };
>  
> @@ -158,7 +160,7 @@ static struct master *__master_find(struct device *dev,
>  }
>  
>  static struct component *find_component(struct master *master,
> -	int (*compare)(struct device *, void *), void *compare_data)
> +	struct component_match_array *mc)
>  {
>  	struct component *c;
>  
> @@ -166,7 +168,11 @@ static struct component *find_component(struct master *master,
>  		if (c->master && c->master != master)
>  			continue;
>  
> -		if (compare(c->dev, compare_data))
> +		if (mc->compare && mc->compare(c->dev, mc->data))
> +			return c;
> +
> +		if (mc->compare_typed &&
> +		    mc->compare_typed(c->dev, c->subcomponent, mc->data))
>  			return c;
>  	}
>  
> @@ -192,7 +198,7 @@ static int find_components(struct master *master)
>  		if (match->compare[i].component)
>  			continue;
>  
> -		c = find_component(master, mc->compare, mc->data);
> +		c = find_component(master, mc);
>  		if (!c) {
>  			ret = -ENXIO;
>  			break;
> @@ -327,29 +333,12 @@ static int component_match_realloc(struct device *dev,
>  	return 0;
>  }
>  
> -/**
> - * component_match_add_release - add a component match with release callback
> - * @master: device with the aggregate driver
> - * @matchptr: pointer to the list of component matches
> - * @release: release function for @compare_data
> - * @compare: compare function to match against all components
> - * @compare_data: opaque pointer passed to the @compare function
> - *
> - * Adds a new component match to the list stored in @matchptr, which the @master
> - * aggregate driver needs to function. The list of component matches pointed to
> - * by @matchptr must be initialized to NULL before adding the first match.
> - *
> - * The allocated match list in @matchptr is automatically released using devm
> - * actions, where upon @release will be called to free any references held by
> - * @compare_data, e.g. when @compare_data is a &device_node that must be
> - * released with of_node_put().
> - *
> - * See also component_match_add().
> - */
> -void component_match_add_release(struct device *master,
> +static void __component_match_add(struct device *master,
>  	struct component_match **matchptr,
>  	void (*release)(struct device *, void *),
> -	int (*compare)(struct device *, void *), void *compare_data)
> +	int (*compare)(struct device *, void *),
> +	int (*compare_typed)(struct device *, int, void *),
> +	void *compare_data)
>  {
>  	struct component_match *match = *matchptr;
>  
> @@ -381,13 +370,69 @@ void component_match_add_release(struct device *master,
>  	}
>  
>  	match->compare[match->num].compare = compare;
> +	match->compare[match->num].compare_typed = compare_typed;
>  	match->compare[match->num].release = release;
>  	match->compare[match->num].data = compare_data;
>  	match->compare[match->num].component = NULL;
>  	match->num++;
>  }
> +
> +/**
> + * component_match_add_release - add a component match with release callback
> + * @master: device with the aggregate driver
> + * @matchptr: pointer to the list of component matches
> + * @release: release function for @compare_data
> + * @compare: compare function to match against all components
> + * @compare_data: opaque pointer passed to the @compare function
> + *
> + * Adds a new component match to the list stored in @matchptr, which the @master
> + * aggregate driver needs to function. The list of component matches pointed to
> + * by @matchptr must be initialized to NULL before adding the first match. This
> + * only matches against components added with component_add().
> + *
> + * The allocated match list in @matchptr is automatically released using devm
> + * actions, where upon @release will be called to free any references held by
> + * @compare_data, e.g. when @compare_data is a &device_node that must be
> + * released with of_node_put().
> + *
> + * See also component_match_add() and component_match_add_typed().
> + */
> +void component_match_add_release(struct device *master,
> +	struct component_match **matchptr,
> +	void (*release)(struct device *, void *),
> +	int (*compare)(struct device *, void *), void *compare_data)
> +{
> +	__component_match_add(master, matchptr, release, compare, NULL,
> +			      compare_data);
> +}
>  EXPORT_SYMBOL(component_match_add_release);
>  
> +/**
> + * component_match_add_typed - add a compent match for a typed component
> + * @master: device with the aggregate driver
> + * @matchptr: pointer to the list of component matches
> + * @compare_typed: compare function to match against all typed components
> + * @compare_data: opaque pointer passed to the @compare function
> + *
> + * Adds a new component match to the list stored in @matchptr, which the @master
> + * aggregate driver needs to function. The list of component matches pointed to
> + * by @matchptr must be initialized to NULL before adding the first match. This
> + * only matches against components added with component_add_typed().
> + *
> + * The allocated match list in @matchptr is automatically released using devm
> + * actions.
> + *
> + * See also component_match_add_release() and component_match_add_typed().
> + */
> +void component_match_add_typed(struct device *master,
> +	struct component_match **matchptr,
> +	int (*compare_typed)(struct device *, int, void *), void *compare_data)
> +{
> +	__component_match_add(master, matchptr, NULL, NULL, compare_typed,
> +			      compare_data);

You're still passing some compare data in that may need to be released,
but you are explicitly denying the ability to provide a release
function pointer here.  What was the reasoning behind that decision?
If someone wanted to use this with compare_data being a device_node,
how should that be handled?

Thanks.

> +}
> +EXPORT_SYMBOL(component_match_add_typed);
> +
>  static void free_master(struct master *master)
>  {
>  	struct component_match *match = master->match;
> @@ -616,19 +661,8 @@ int component_bind_all(struct device *master_dev, void *data)
>  }
>  EXPORT_SYMBOL_GPL(component_bind_all);
>  
> -/**
> - * component_add - register a component
> - * @dev: component device
> - * @ops: component callbacks
> - *
> - * Register a new component for @dev. Functions in @ops will be called when the
> - * aggregate driver is ready to bind the overall driver by calling
> - * component_bind_all(). See also &struct component_ops.
> - *
> - * The component needs to be unregistered at driver unload/disconnect by calling
> - * component_del().
> - */
> -int component_add(struct device *dev, const struct component_ops *ops)
> +static int __component_add(struct device *dev, const struct component_ops *ops,
> +	int subcomponent)
>  {
>  	struct component *component;
>  	int ret;
> @@ -639,6 +673,7 @@ int component_add(struct device *dev, const struct component_ops *ops)
>  
>  	component->ops = ops;
>  	component->dev = dev;
> +	component->subcomponent = subcomponent;
>  
>  	dev_dbg(dev, "adding component (ops %ps)\n", ops);
>  
> @@ -657,6 +692,55 @@ int component_add(struct device *dev, const struct component_ops *ops)
>  
>  	return ret < 0 ? ret : 0;
>  }
> +
> +/**
> + * component_add_typed - register a component
> + * @dev: component device
> + * @ops: component callbacks
> + * @subcomponent: nonzero identifier for subcomponents
> + *
> + * Register a new component for @dev. Functions in @ops will be call when the
> + * aggregate driver is ready to bind the overall driver by calling
> + * component_bind_all(). See also &struct component_ops.
> + *
> + * @subcomponent must be nonzero and is used to differentiate between multiple
> + * components registerd on the same device @dev. These components are match
> + * using component_match_add_typed().
> + *
> + * The component needs to be unregistered at driver unload/disconnect by
> + * calling component_del().
> + *
> + * See also component_add().
> + */
> +int component_add_typed(struct device *dev, const struct component_ops *ops,
> +	int subcomponent)
> +{
> +	if (WARN_ON(subcomponent == 0))
> +		return -EINVAL;
> +
> +	return __component_add(dev, ops, subcomponent);
> +}
> +EXPORT_SYMBOL_GPL(component_add_typed);
> +
> +/**
> + * component_add - register a component
> + * @dev: component device
> + * @ops: component callbacks
> + *
> + * Register a new component for @dev. Functions in @ops will be called when the
> + * aggregate driver is ready to bind the overall driver by calling
> + * component_bind_all(). See also &struct component_ops.
> + *
> + * The component needs to be unregistered at driver unload/disconnect by
> + * calling component_del().
> + *
> + * See also component_add_typed() for a variant that allows multipled different
> + * components on the same device.
> + */
> +int component_add(struct device *dev, const struct component_ops *ops)
> +{
> +	return __component_add(dev, ops, 0);
> +}
>  EXPORT_SYMBOL_GPL(component_add);
>  
>  /**
> diff --git a/include/linux/component.h b/include/linux/component.h
> index 83da25bdf59c..30bcc7e590eb 100644
> --- a/include/linux/component.h
> +++ b/include/linux/component.h
> @@ -34,6 +34,8 @@ struct component_ops {
>  };
>  
>  int component_add(struct device *, const struct component_ops *);
> +int component_add_typed(struct device *dev, const struct component_ops *ops,
> +	int subcomponent);
>  void component_del(struct device *, const struct component_ops *);
>  
>  int component_bind_all(struct device *master, void *master_data);
> @@ -91,6 +93,9 @@ void component_match_add_release(struct device *master,
>  	struct component_match **matchptr,
>  	void (*release)(struct device *, void *),
>  	int (*compare)(struct device *, void *), void *compare_data);
> +void component_match_add_typed(struct device *master,
> +	struct component_match **matchptr,
> +	int (*compare_typed)(struct device *, int, void *), void *compare_data);
>  
>  /**
>   * component_match_add - add a compent match
> @@ -101,12 +106,13 @@ void component_match_add_release(struct device *master,
>   *
>   * Adds a new component match to the list stored in @matchptr, which the @master
>   * aggregate driver needs to function. The list of component matches pointed to
> - * by @matchptr must be initialized to NULL before adding the first match.
> + * by @matchptr must be initialized to NULL before adding the first match. This
> + * only matches against components added with component_add().
>   *
>   * The allocated match list in @matchptr is automatically released using devm
>   * actions.
>   *
> - * See also component_match_add_release().
> + * See also component_match_add_release() and component_match_add_typed().
>   */
>  static inline void component_match_add(struct device *master,
>  	struct component_match **matchptr,
> -- 
> 2.20.1
> 
> 

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