Re: [PATCHv2 1/9] media: Fix DVB representation at media controller API

[Laurent Pinchart <laurent.pinchart-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org>]

Hi Mauro,

On Sunday 11 January 2015 11:58:24 Mauro Carvalho Chehab wrote:
> Em Sun, 11 Jan 2015 15:50:04 +0200 Laurent Pinchart escreveu:
> > On Saturday 03 January 2015 12:49:03 Mauro Carvalho Chehab wrote:
> >> The DVB devices are identified via a (major, minor) tuple,
> >> and not by a random id. Fix it, before we start using it.
> >> 
> >> Signed-off-by: Mauro Carvalho Chehab <mchehab-JPH+aEBZ4P+UEJcrhfAQsw@public.gmane.org>
> >> 
> >> diff --git a/include/media/media-entity.h b/include/media/media-entity.h
> >> index e00459185d20..de333cc8261b 100644
> >> --- a/include/media/media-entity.h
> >> +++ b/include/media/media-entity.h
> >> @@ -97,7 +97,10 @@ struct media_entity {
> >>  			u32 device;
> >>  			u32 subdevice;
> >>  		} alsa;
> >> -		int dvb;
> >> +		struct {
> >> +			u32 major;
> >> +			u32 minor;
> >> +		} dvb;
> >> 
> >>  		/* Sub-device specifications */
> >>  		/* Nothing needed yet */
> >> diff --git a/include/uapi/linux/media.h b/include/uapi/linux/media.h
> >> index d847c760e8f0..7902e800f019 100644
> >> --- a/include/uapi/linux/media.h
> >> +++ b/include/uapi/linux/media.h
> >> @@ -27,7 +27,7 @@
> >>  #include <linux/types.h>
> >>  #include <linux/version.h>
> >> 
> >> -#define MEDIA_API_VERSION	KERNEL_VERSION(0, 1, 0)
> >> +#define MEDIA_API_VERSION	KERNEL_VERSION(0, 1, 1)
> >> 
> >>  struct media_device_info {
> >>  	char driver[16];
> >> @@ -88,7 +88,10 @@ struct media_entity_desc {
> >>  			__u32 device;
> >>  			__u32 subdevice;
> >>  		} alsa;
> >> -		int dvb;
> >> +		struct {
> >> +			__u32 major;
> >> +			__u32 minor;
> >> +		} dvb;
> > 
> > Won't this break compilation of existing userspace code ? As DVB is not
> > properly supported in MC at the moment we could consider that only
> > mediactl will be affected, so it shouldn't be a big issue.
> 
> Well, media-ctl uses a local copy of the videodev2.h header, so it won't
> break.

It's media.h, but you're correct here.

> I'm not aware of any other application using MC for DVB.
> 
> Yet, imagining that such application exists, then, IMHO, it is better
> to break compilation for it, as probably such application was written for
> some OOT driver that might be using its own version of the media
> controller implementation.

OK. I'll remember that argument the next time I want to break a kernel API 
though ;-)

-- 
Regards,

Laurent Pinchart