On Friday 01 May 2009 04:21:36 Andy Walls wrote: > On Wed, 2009-04-29 at 21:18 -0400, Andy Walls wrote: > > On Wed, 2009-04-29 at 13:33 +0200, Hans Verkuil wrote: > > > > On Wed, 2009-04-29 at 21:50 +1200, Michael Cree wrote: > > > >> On 29/04/2009, at 6:19 PM, Hans Verkuil wrote: > > > >> > What does surprise me here is that the fw is loaded right after > > > >> > the driver > > > >> > was loaded, which does suggest that some process is opening one > > > >> > of the device nodes since the fw load is only done on the first > > > >> > open. > > > > > > > > On my systems (Fedora 9 & 10) IIRC it happens early too. I've > > > > always assumed it was either udev or hal or some some other > > > > automatic process that mucks with device nodes. > > > > > > It would be nice if you could track down who is messing around with > > > those device nodes. > > > > I'll work on it. It looks like something that is aware of v4l device > > nodes (see below) - I'm wagering hald. > > I've found it. It's hald-probe-video4linux: > > [11539.917539] cx18-0: info: cx18_v4l2_open: called for stream encoder > MPEG by pid 22870 (hald-probe-vide) ppid 1981 (hald-runner) > [11540.333557] cx18-0: info: cx18_v4l2_open: called for stream encoder > PCM audio by pid 22907 (hald-probe-vide) ppid 1981 (hald-runner) > [11540.337019] cx18-0: info: cx18_v4l2_open: called for stream encoder > VBI by pid 22923 (hald-probe-vide) ppid 1981 (hald-runner) [11540.386051] > cx18-0: info: cx18_v4l2_open: called for stream encoder YUV by pid 22929 > (hald-probe-vide) ppid 1981 (hald-runner) [11540.401658] cx18-0: info: > cx18_v4l2_open: called for stream encoder radio by pid 22930 > (hald-probe-vide) ppid 1981 (hald-runner) > > # locate hald-probe-vide > /usr/libexec/hald-probe-video4linux > > > It's not restricted to boot. It happens on modprobe, probably cued by > udev or some other hotplug mechanism. > > > > If you modprobe ivtv with file and ioctl debugging on, does > > > that give an indication of what is done with the device nodes? > > > > For the cx18 driver on a Fedora 10 system something runs through > > the /dev/video* nodes and /dev/radio* doing VIDIOC_QUERYCAP. I suspect > > the behavior will be the same for ivtv. I'll test on my other system > > when I get a chance. > > > > > Depending on what process is doing what with the device nodes I may > > > be able to optimize the driver for that. It's really annoying to have > > > this fw loaded at boot time, esp. if you have one or more PVR-500 > > > cards. > > Well thinking about this, this is a system level issue: > > 1. People want to avoid unnecessary waits at boot (or module insertion > time) > > 2. Hardware detection mechanisms want to query what new hardware is as > soon as it appears. > > 3. Hardware queries from userspace should (or need to) avoid IO bound > operations that consume CPU. > > 4. Kernel drivers should be able to satsify hardware queries without > starting up an IO bound operation that consumes CPU. > > Hans, it sounds like your media_controller device node idea is really > what we need to get implemented here for user space to do queires on > hardware. This problem obviously affects more than the ivtv driver so > I'd recommend against an ivtv band-aid. > > We'd also want to coordinate with the hald folks and other user space > app/plumbing developers, as this likely affects a few v4l2 drivers. It > sounds like an LPC agenda item to me... > > Regards, > Andy I agree. A media controller device is exactly what we need. It's ideal for applications and daemons like hald. Now all I need is the time to work on it and I don't see that happening anytime soon. :-( Any volunteers? I have a general idea of how it should be implemented, but it needs a fair amount of research as well. Regards, Hans -- Hans Verkuil - video4linux developer - sponsored by TANDBERG Telecom -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
