[PATCH] extcon: Add EXTCON_MECHANICAL cable type for physical presence

[PATCH] extcon: Add EXTCON_MECHANICAL cable type for physical presence

[Mark Brown]

Some accessory detection mechanisms are able to detect that something is
physically present in the socket separately to identifying what is present
in the socket. This information can be useful to applications, for example
allowing them to indicate that a potentially broken accessory is present,
so provide a standard way to report it to userspace.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
---
 drivers/extcon/extcon_class.c |    1 +
 include/linux/extcon.h        |    1 +
 2 files changed, 2 insertions(+)

diff --git a/drivers/extcon/extcon_class.c b/drivers/extcon/extcon_class.c
index 53c64a9..a7116e8 100644
--- a/drivers/extcon/extcon_class.c
+++ b/drivers/extcon/extcon_class.c
@@ -60,6 +60,7 @@ const char *extcon_cable_name[] = {
 	[EXTCON_SPDIF_OUT]	= "SPDIF-out",
 	[EXTCON_VIDEO_IN]	= "Video-in",
 	[EXTCON_VIDEO_OUT]	= "Video-out",
+	[EXTCON_MECHANICAL]	= "Mechanical",
 
 	NULL,
 };
diff --git a/include/linux/extcon.h b/include/linux/extcon.h
index 6495f77..cdd4014 100644
--- a/include/linux/extcon.h
+++ b/include/linux/extcon.h
@@ -66,6 +66,7 @@ enum extcon_cable_name {
 	EXTCON_SPDIF_OUT,
 	EXTCON_VIDEO_IN,
 	EXTCON_VIDEO_OUT,
+	EXTCON_MECHANICAL,
 };
 extern const char *extcon_cable_name[];
 
-- 
1.7.10

Re: [PATCH] extcon: Add EXTCON_MECHANICAL cable type for physical presence

[Greg Kroah-Hartman]

On Wed, May 02, 2012 at 10:38:51AM +0100, Mark Brown wrote:
> Some accessory detection mechanisms are able to detect that something is
> physically present in the socket separately to identifying what is present
> in the socket. This information can be useful to applications, for example
> allowing them to indicate that a potentially broken accessory is present,
> so provide a standard way to report it to userspace.
> 
> Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
> ---
>  drivers/extcon/extcon_class.c |    1 +
>  include/linux/extcon.h        |    1 +
>  2 files changed, 2 insertions(+)

Ok, but where is the in-kernel user of this new interface?  Why are we
adding it now before someone actually needs it?

And shouldn't this also update some documentation somewhere as well?

thanks,

greg k-h

Re: [PATCH] extcon: Add EXTCON_MECHANICAL cable type for physical presence

[Mark Brown]

On Wed, May 02, 2012 at 01:13:21PM -0700, Greg Kroah-Hartman wrote:

> Ok, but where is the in-kernel user of this new interface?  Why are we
> adding it now before someone actually needs it?

Well, one could say the same thing about the entire interface right now
but if you look at the existing accessory detection abstraction for
sound cards in include/sound/jack.h and the input API that's currently
the only userspace API for it you can see that they have this feature
already.

There's a reasonable prospect of the ALSA abstraction getting support
for extcon at some point in the not too distant future at which point it
will acquire all the users that has but I'd not anticipate that until
after the merge window as the ALSA stuff wants some prodding and poking 
prior to doing that which I really hope will collide with some other
updates too.

> And shouldn't this also update some documentation somewhere as well?

There doesn't appear to be any existing relevant documentation to
update, and to be honest given that what we're doing is mapping a plain
text name into a constant I'm not sure it'd be adding much.