[PATCH] rc-core: improve the lirc protocol reporting

[PATCH] rc-core: improve the lirc protocol reporting

[David Härdeman]

Commit 275ddb40bcf686d210d86c6718e42425a6a0bc76 removed the lirc
"protocol" but kept backwards compatibility by always listing
the protocol as present and enabled. This patch further improves
the logic by only listing the protocol if the lirc module is loaded
(or if lirc is builtin).

Signed-off-by: David Härdeman <david@hardeman.nu>
---
 drivers/media/rc/rc-main.c |   19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/drivers/media/rc/rc-main.c b/drivers/media/rc/rc-main.c
index ecaee02..3f0f71a 100644
--- a/drivers/media/rc/rc-main.c
+++ b/drivers/media/rc/rc-main.c
@@ -828,6 +828,23 @@ struct rc_filter_attribute {
 		.mask = (_mask),					\
 	}
 
+static bool lirc_is_present(void)
+{
+#if defined(CONFIG_LIRC_MODULE)
+	struct module *lirc;
+
+	mutex_lock(&module_mutex);
+	lirc = find_module("lirc_dev");
+	mutex_unlock(&module_mutex);
+
+	return lirc ? true : false;
+#elif defined(CONFIG_LIRC)
+	return true;
+#else
+	return false;
+#endif
+}
+
 /**
  * show_protocols() - shows the current/wakeup IR protocol(s)
  * @device:	the device descriptor
@@ -882,7 +899,7 @@ static ssize_t show_protocols(struct device *device,
 			allowed &= ~proto_names[i].type;
 	}
 
-	if (dev->driver_type == RC_DRIVER_IR_RAW)
+	if (dev->driver_type == RC_DRIVER_IR_RAW && lirc_is_present())
 		tmp += sprintf(tmp, "[lirc] ");
 
 	if (tmp != buf)

Re: [PATCH] rc-core: improve the lirc protocol reporting

[Mauro Carvalho Chehab]

Hi David,

Em Wed, 22 Jul 2015 22:55:24 +0200
David Härdeman <david@hardeman.nu> escreveu:

> Commit 275ddb40bcf686d210d86c6718e42425a6a0bc76 removed the lirc
> "protocol" but kept backwards compatibility by always listing
> the protocol as present and enabled. This patch further improves
> the logic by only listing the protocol if the lirc module is loaded
> (or if lirc is builtin).

Makes sense, but see below.

> 
> Signed-off-by: David Härdeman <david@hardeman.nu>
> ---
>  drivers/media/rc/rc-main.c |   19 ++++++++++++++++++-
>  1 file changed, 18 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/rc/rc-main.c b/drivers/media/rc/rc-main.c
> index ecaee02..3f0f71a 100644
> --- a/drivers/media/rc/rc-main.c
> +++ b/drivers/media/rc/rc-main.c
> @@ -828,6 +828,23 @@ struct rc_filter_attribute {
>  		.mask = (_mask),					\
>  	}
>  
> +static bool lirc_is_present(void)
> +{
> +#if defined(CONFIG_LIRC_MODULE)
> +	struct module *lirc;
> +
> +	mutex_lock(&module_mutex);
> +	lirc = find_module("lirc_dev");
> +	mutex_unlock(&module_mutex);

I don't think it would be a good idea to play with the module mutex
lock here or calling find_module(). This is something that no other driver
does (well, except for FB DRM driver, that dynamically loads a module
if not found).

Perhaps we could use some simpler logic, like storing some value if lirc
got loaded or not (worse case, we might use a static atomic var at rc core).

> +
> +	return lirc ? true : false;
> +#elif defined(CONFIG_LIRC)
> +	return true;
> +#else
> +	return false;
> +#endif
> +}
> +
>  /**
>   * show_protocols() - shows the current/wakeup IR protocol(s)
>   * @device:	the device descriptor
> @@ -882,7 +899,7 @@ static ssize_t show_protocols(struct device *device,
>  			allowed &= ~proto_names[i].type;
>  	}
>  
> -	if (dev->driver_type == RC_DRIVER_IR_RAW)
> +	if (dev->driver_type == RC_DRIVER_IR_RAW && lirc_is_present())
>  		tmp += sprintf(tmp, "[lirc] ");
>  
>  	if (tmp != buf)
> 
> --
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