[PATCH v2 1/2] [media] rc-core: Add inlined stubs for core rc_* functions

[PATCH v2 1/2] [media] rc-core: Add inlined stubs for core rc_* functions

[Lee Jones]

Currently users have to use all sorts of ugly #ifery within
their drivers in order to avoid linking issues at build time.
This patch allows users to safely call these functions when
!CONFIG_RC_CORE and make decisions based on the return value
instead.  This is a much more common and clean way of doing
things within the Linux kernel.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
---

v1 => v2
  - Use '#if IF_ENABLED()' instead of '#ifdef' in order to do the
    right thing, even when CONFIG_RC_CORE=m.
  
include/media/rc-core.h | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/include/media/rc-core.h b/include/media/rc-core.h
index 73ddd721..f176a9e 100644
--- a/include/media/rc-core.h
+++ b/include/media/rc-core.h
@@ -209,7 +209,14 @@ struct rc_dev {
  * @rc_driver_type: specifies the type of the RC output to be allocated
  * returns a pointer to struct rc_dev.
  */
+#if IS_ENABLED(CONFIG_RC_CORE)
 struct rc_dev *rc_allocate_device(enum rc_driver_type);
+#else
+static inline struct rc_dev *rc_allocate_device(int unused)
+{
+	return NULL;
+}
+#endif
 
 /**
  * devm_rc_allocate_device - Managed RC device allocation
@@ -218,21 +225,42 @@ struct rc_dev *rc_allocate_device(enum rc_driver_type);
  * @rc_driver_type: specifies the type of the RC output to be allocated
  * returns a pointer to struct rc_dev.
  */
+#if IS_ENABLED(CONFIG_RC_CORE)
 struct rc_dev *devm_rc_allocate_device(struct device *dev, enum rc_driver_type);
+#else
+static inline struct rc_dev *devm_rc_allocate_device(struct device *dev, int unused)
+{
+	return NULL;
+}
+#endif
 
 /**
  * rc_free_device - Frees a RC device
  *
  * @dev: pointer to struct rc_dev.
  */
+#if IS_ENABLED(CONFIG_RC_CORE)
 void rc_free_device(struct rc_dev *dev);
+#else
+static inline void rc_free_device(struct rc_dev *dev)
+{
+	return;
+}
+#endif
 
 /**
  * rc_register_device - Registers a RC device
  *
  * @dev: pointer to struct rc_dev.
  */
+#if IS_ENABLED(CONFIG_RC_CORE)
 int rc_register_device(struct rc_dev *dev);
+#else
+static inline int rc_register_device(struct rc_dev *dev)
+{
+	return -EOPNOTSUPP;
+}
+#endif
 
 /**
  * devm_rc_register_device - Manageded registering of a RC device
@@ -240,14 +268,28 @@ int rc_register_device(struct rc_dev *dev);
  * @parent: pointer to struct device.
  * @dev: pointer to struct rc_dev.
  */
+#if IS_ENABLED(CONFIG_RC_CORE)
 int devm_rc_register_device(struct device *parent, struct rc_dev *dev);
+#else
+static inline int devm_rc_register_device(struct device *parent, struct rc_dev *dev)
+{
+	return -EOPNOTSUPP;
+}
+#endif
 
 /**
  * rc_unregister_device - Unregisters a RC device
  *
  * @dev: pointer to struct rc_dev.
  */
+#if IS_ENABLED(CONFIG_RC_CORE)
 void rc_unregister_device(struct rc_dev *dev);
+#else
+static inline void rc_unregister_device(struct rc_dev *dev)
+{
+	return;
+}
+#endif
 
 /**
  * rc_open - Opens a RC device
-- 
2.9.3

[PATCH v2 2/2] [media] cec: Handle RC capability more elegantly

[Lee Jones]

If a user specifies the use of RC as a capability, they should
really be enabling RC Core code.  If they do not we WARN() them
of this and disable the capability for them.

Once we know RC Core code has not been enabled, we can update
the user's capabilities and use them as a term of reference for
other RC-only calls.  This is preferable to having ugly #ifery
scattered throughout C code.

Most of the functions are actually safe to call, since they
sensibly check for a NULL RC pointer before they attempt to
deference it.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
 drivers/media/cec/cec-core.c | 21 +++++++++------------
 1 file changed, 9 insertions(+), 12 deletions(-)

diff --git a/drivers/media/cec/cec-core.c b/drivers/media/cec/cec-core.c
index cfe414a..c859dcf 100644
--- a/drivers/media/cec/cec-core.c
+++ b/drivers/media/cec/cec-core.c
@@ -208,9 +208,15 @@ struct cec_adapter *cec_allocate_adapter(const struct cec_adap_ops *ops,
 		return ERR_PTR(-EINVAL);
 	if (WARN_ON(!available_las || available_las > CEC_MAX_LOG_ADDRS))
 		return ERR_PTR(-EINVAL);
+
+	/* If RC Core is not available, remove driver-level capability */
+	if (!IS_REACHABLE(CONFIG_RC_CORE))
+		caps &= ~CEC_CAP_RC;
+
 	adap = kzalloc(sizeof(*adap), GFP_KERNEL);
 	if (!adap)
 		return ERR_PTR(-ENOMEM);
+
 	strlcpy(adap->name, name, sizeof(adap->name));
 	adap->phys_addr = CEC_PHYS_ADDR_INVALID;
 	adap->log_addrs.cec_version = CEC_OP_CEC_VERSION_2_0;
@@ -237,7 +243,6 @@ struct cec_adapter *cec_allocate_adapter(const struct cec_adap_ops *ops,
 	if (!(caps & CEC_CAP_RC))
 		return adap;
 
-#if IS_REACHABLE(CONFIG_RC_CORE)
 	/* Prepare the RC input device */
 	adap->rc = rc_allocate_device(RC_DRIVER_SCANCODE);
 	if (!adap->rc) {
@@ -264,9 +269,7 @@ struct cec_adapter *cec_allocate_adapter(const struct cec_adap_ops *ops,
 	adap->rc->priv = adap;
 	adap->rc->map_name = RC_MAP_CEC;
 	adap->rc->timeout = MS_TO_NS(100);
-#else
-	adap->capabilities &= ~CEC_CAP_RC;
-#endif
+
 	return adap;
 }
 EXPORT_SYMBOL_GPL(cec_allocate_adapter);
@@ -285,7 +288,6 @@ int cec_register_adapter(struct cec_adapter *adap,
 	adap->owner = parent->driver->owner;
 	adap->devnode.dev.parent = parent;
 
-#if IS_REACHABLE(CONFIG_RC_CORE)
 	if (adap->capabilities & CEC_CAP_RC) {
 		adap->rc->dev.parent = parent;
 		res = rc_register_device(adap->rc);
@@ -298,15 +300,13 @@ int cec_register_adapter(struct cec_adapter *adap,
 			return res;
 		}
 	}
-#endif
 
 	res = cec_devnode_register(&adap->devnode, adap->owner);
 	if (res) {
-#if IS_REACHABLE(CONFIG_RC_CORE)
 		/* Note: rc_unregister also calls rc_free */
 		rc_unregister_device(adap->rc);
 		adap->rc = NULL;
-#endif
+
 		return res;
 	}
 
@@ -337,11 +337,10 @@ void cec_unregister_adapter(struct cec_adapter *adap)
 	if (IS_ERR_OR_NULL(adap))
 		return;
 
-#if IS_REACHABLE(CONFIG_RC_CORE)
 	/* Note: rc_unregister also calls rc_free */
 	rc_unregister_device(adap->rc);
 	adap->rc = NULL;
-#endif
+
 	debugfs_remove_recursive(adap->cec_dir);
 	cec_devnode_unregister(&adap->devnode);
 }
@@ -357,9 +356,7 @@ void cec_delete_adapter(struct cec_adapter *adap)
 	kthread_stop(adap->kthread);
 	if (adap->kthread_config)
 		kthread_stop(adap->kthread_config);
-#if IS_REACHABLE(CONFIG_RC_CORE)
 	rc_free_device(adap->rc);
-#endif
 	kfree(adap);
 }
 EXPORT_SYMBOL_GPL(cec_delete_adapter);
-- 
2.9.3

Re: [PATCH v2 1/2] [media] rc-core: Add inlined stubs for core rc_* functions

[Lee Jones]

On Wed, 12 Apr 2017, Lee Jones wrote:

> Currently users have to use all sorts of ugly #ifery within
> their drivers in order to avoid linking issues at build time.
> This patch allows users to safely call these functions when
> !CONFIG_RC_CORE and make decisions based on the return value
> instead.  This is a much more common and clean way of doing
> things within the Linux kernel.
> 
> Signed-off-by: Lee Jones <lee.jones@linaro.org>
> ---
> 
> v1 => v2
>   - Use '#if IF_ENABLED()' instead of '#ifdef' in order to do the
>     right thing, even when CONFIG_RC_CORE=m.
>   
> include/media/rc-core.h | 42 ++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 42 insertions(+)

Hans,

What are your plans for this patch set?  Removal of #ifery from C
files has to be seen as an improvement, thus I see no reason why they
wouldn't be accepted.

Please advise.

> diff --git a/include/media/rc-core.h b/include/media/rc-core.h
> index 73ddd721..f176a9e 100644
> --- a/include/media/rc-core.h
> +++ b/include/media/rc-core.h
> @@ -209,7 +209,14 @@ struct rc_dev {
>   * @rc_driver_type: specifies the type of the RC output to be allocated
>   * returns a pointer to struct rc_dev.
>   */
> +#if IS_ENABLED(CONFIG_RC_CORE)
>  struct rc_dev *rc_allocate_device(enum rc_driver_type);
> +#else
> +static inline struct rc_dev *rc_allocate_device(int unused)
> +{
> +	return NULL;
> +}
> +#endif
>  
>  /**
>   * devm_rc_allocate_device - Managed RC device allocation
> @@ -218,21 +225,42 @@ struct rc_dev *rc_allocate_device(enum rc_driver_type);
>   * @rc_driver_type: specifies the type of the RC output to be allocated
>   * returns a pointer to struct rc_dev.
>   */
> +#if IS_ENABLED(CONFIG_RC_CORE)
>  struct rc_dev *devm_rc_allocate_device(struct device *dev, enum rc_driver_type);
> +#else
> +static inline struct rc_dev *devm_rc_allocate_device(struct device *dev, int unused)
> +{
> +	return NULL;
> +}
> +#endif
>  
>  /**
>   * rc_free_device - Frees a RC device
>   *
>   * @dev: pointer to struct rc_dev.
>   */
> +#if IS_ENABLED(CONFIG_RC_CORE)
>  void rc_free_device(struct rc_dev *dev);
> +#else
> +static inline void rc_free_device(struct rc_dev *dev)
> +{
> +	return;
> +}
> +#endif
>  
>  /**
>   * rc_register_device - Registers a RC device
>   *
>   * @dev: pointer to struct rc_dev.
>   */
> +#if IS_ENABLED(CONFIG_RC_CORE)
>  int rc_register_device(struct rc_dev *dev);
> +#else
> +static inline int rc_register_device(struct rc_dev *dev)
> +{
> +	return -EOPNOTSUPP;
> +}
> +#endif
>  
>  /**
>   * devm_rc_register_device - Manageded registering of a RC device
> @@ -240,14 +268,28 @@ int rc_register_device(struct rc_dev *dev);
>   * @parent: pointer to struct device.
>   * @dev: pointer to struct rc_dev.
>   */
> +#if IS_ENABLED(CONFIG_RC_CORE)
>  int devm_rc_register_device(struct device *parent, struct rc_dev *dev);
> +#else
> +static inline int devm_rc_register_device(struct device *parent, struct rc_dev *dev)
> +{
> +	return -EOPNOTSUPP;
> +}
> +#endif
>  
>  /**
>   * rc_unregister_device - Unregisters a RC device
>   *
>   * @dev: pointer to struct rc_dev.
>   */
> +#if IS_ENABLED(CONFIG_RC_CORE)
>  void rc_unregister_device(struct rc_dev *dev);
> +#else
> +static inline void rc_unregister_device(struct rc_dev *dev)
> +{
> +	return;
> +}
> +#endif
>  
>  /**
>   * rc_open - Opens a RC device

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog