[mythtv] Mythtv and kernel 2.6.25

[Paulo Cavalcanti]

On Tue, Jun 24, 2008 at 2:31 PM, Andrew M. Bishop <amb at gedanken.demon.co.uk>
wrote:

> "Paulo Cavalcanti" <promac at gmail.com> writes:
>
> > On Sun, Jun 22, 2008 at 6:56 AM, Andrew M. Bishop <
> amb at gedanken.demon.co.uk>
> > wrote:
> >
> >> "Paulo Cavalcanti" <promac at gmail.com> writes:
> >>
> >> >> > I am having problems to make mythtv work with kernel 2.6.25 (Fedora
> 8).
> >> >> >
> >> >> > The problem seems to be my capture card, a Prolink Pixelview.
>
> >> I had the same problem and stayed on kernel 2.6.24 with my bttv cards.
> >> I did some investigation and the problem seems to be related to the
> >> changeover to V4L2 in 2.6.25.
> >>
> >> This message http://lkml.org/lkml/2008/1/6/83 describes a patch to the
> >> bttv driver, but if you look at the 2.6.25 kernel source you will see
> >> that it isn't there.  If you apply this patch (like I tried) then it
> >> will get further, it won't lockup but I didn't get any video either.
>
> > I rebuilt video4linux from ATrpms using today's snapshot,
> > and it worked.
> >
> > Well, almost. If I try mythtv Live TV after rebooting, I get a green
> screen
> > (but no lock).
>
> This is what I got when I tried my home-made patch with the raw 2.6.25
> kernel - a green screen instead of a picture.
>
> I enabled all of the debugging that I could find and this was the
> error message that I was getting:
>
> v4l1-compat: VIDIOCMCAPTURE / VIDIOC_S_FMT: -16
>
>
> To bring this back on topic for mythtv-dev: I think that the problem
> is that mythtv uses partly or mostly V4L1 and with newer kernels this
> is provided only by a compatibility layer.  The VIDIOCGMBUF and
> VIDIOCMCAPTURE ioctls (which are the ones causing the two problems
> here) are both V4L1.  If the V4L1 layer ever goes away then mythtv
> will need to switch over.
>
>
> > However, If I run mplayer before using mythtv, Live TV works just fine.
> > Maybe this is related to the nvidia driver I am using. I did not try the
> > latest one (173.14.09).
> >
> > I will ask Axel to make video4linux (20080622) available to the public.
>
> Probably this configures the tuner in some way that is different from
> mythtv and the settings stick.
>


Hi,

ATrpms has the updated video4linux tree (20080622).
Therefore, it is easy to test without getting locks. One just need
to install the appropriate video4linux kmdl.

I also contacted Mauro Chehab:

> Hi, Mauro
>
> I almost got mythtv working again with bttv and kernel 2.6.25
>
> http://mythtv.org/pipermail/mythtv-dev/2008-June/062323.html
>
> http://mythtv.org/pipermail/mythtv-dev/2008-June/062325.html
>
> However, I have to run an mplayer (second link above) script before
> using mythtv with Live TV. Otherwise, I get only a green screen.
>
> Can you give me a clue why the script fix the problem?

>> Weird. There are some possible reasons for a green screen:

>>        1) xv troubles. This sometimes happens if you are using a
proprietary
>> driver, like ati or nvidia. Don't use those drivers, or you'll have
troubles
>> displaying tv;

>>        2) Tuner didn't load firmware properly (if you're using
xc2028/xc3028
>> or xc5000);

>>        3) Some analog tuners only work if you set it first to a high
channel.
>> Kernel driver already sets freq to 400KHz, so I suspect that this is not
the case;

>>        4) There are some failure at the negotiation process between
MythTV and
>> your board. Since boards like bttv supports several different formats,
maybe a
>> bug at MythTV is preventing it to select the proper format. Maybe some
API
>> non-compliance could prevent MythTV to find the proper format;

>>       5) a kernel bug ;) Since it is working with other userspace apps, I
>> don't think this is the issue.

>> I've just added a small patch at linuxtv repository that will allow you
to
>> enable ioctl debug at the driver.

>> Please try first to use the non-proprietary driver (if you're using).

>> If still not working, you'll need to retrieve the last version of the
driver at:
>>        http://linuxtv.org/hg/v4l-dvb

>> after compiling/installing, you'll need to do:
>>        modprobe bttv bttv_debug=3

>> Please try to run mythtv without using the mplayer command and send us
the
>> output of "dmesg" command.

>
> Thanks, and keep up with the very good work at video4linux.

>> Anytime.

As I said before, running mplayer for watching TV just once (after
rebooting),
fix the myth Live TV.
My myth seems to be working very well with kernel 2.6.25 after doing that.
I can record, edit, etc ...

I tried running other programs, such as xawtv, tvtime, but only mplayer
fixed the
issue with the Live TV.

Probably, I will only have time to debug the bttv driver next week.
Although I use an nvidia card (GeForce 7600 GS), I do not think the problem
is
because of the proprietary driver. If anyone can run without loading the
nvidia driver (but using the nv driver), I would like to hear the result.

Thanks for the info.

-- 
Paulo Roma Cavalcanti
LCG - UFRJ
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