[linux-dvb] [PATCH] add device node locking possibility to dvbcore

Markus Rechberger mrechberger at gmail.com
Thu Aug 9 19:00:34 CEST 2007


On 8/9/07, Markus Rechberger <mrechberger at gmail.com> wrote:
> On 8/9/07, Steven Toth <stoth at hauppauge.com> wrote:
> > Markus Rechberger wrote:
> > > Following patch adds a rather primitive way to temporary lock dvb
> > > devicenodes, this can be useful for hybrid devices which use the
> > > video4linux framework for the analogue TV part and the dvb framework for
> > > digital TV if only one mode can be accessed at a time.
> > >
> > > Signed-off-by: Markus Rechberger <markus.rechberger at amd.com>
> > >
> > >
> > Call me dumb but I don't understand how this patch helps v4l devices. :)
> >
> > Allocation/management of a single card resource doesn't belong inside
> > the dvb framework, these answers need to come from the bridge-frameworks
> > (via callbacks from dvb-core or the analog equivalent) who are better
> > placed to make the decision about hybrid tuners, bus capacity or
> > allocation, in use devices.
> >
> > As a working example, I added similar support in my older HVR3000 tree
> > where two frontends share a single transport bus. The code is old but it
> > demonstrates a solution, much the my earlier patches for shared
> > DVB/Blackbird boards also.
> >
> > I understand how this patch helps the current dvb tree, it stops
> > multiple people opening a device but that's it. ... Or, maybe I've just
> > missed to point.
> >
>
> Hi Steve,
>
> the bridge framework triggers locking these filehandles.

s/filehandles/nodes/

> http://mcentral.de/hg/~mrec/v4l-dvb-experimental/file/c0817d73a2a9/linux/drivers/media/video/em28xx/em28xx-video.c
>
> line 434
> this locks the dvb nodes if someone tries to open the v4l devicenode,
> it first checks if there's still something active at the DVB side.
>
> http://mcentral.de/hg/~mrec/v4l-dvb-experimental/file/f9f3e6bdd6fc/linux/drivers/media/video/em28xx/em2880-dvb.c
>
> Line 471 - 484 if this would go into the dvb core we'd have a callback
> for locking the device nodes.
>

I  want to allow a user to use one mode at a time, so either DVB or V4L.
The device requires a different firmware for V4L and DVB also
different GPIO values and some special register writes.

Markus



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