[mythtv-users] Card not ready

[Stephen Worthington]

On Sat, 5 Nov 2022 02:53:09 +0000, you wrote:

>On Fri, Nov 4, 2022 at 11:46 PM James <jam at tigger.ws> wrote:
>
>> At the macro level I know what to do, it's the detail ...
>> does instantiation of /dev/dvb/adaperN mean the card IS ready or SOON-WILL-BE ?
>
>In theory (and theory and practice depends
>on the particular driver) the device should be
>ready after it is created, so adding an
>appropriate device specific WANTS and
>AFTER to the BE unit override, and if there
>exists an appropriate udev rule to tag the
>device(s) with the systemd value, things
>should work as expected.
>
>Note that if you are using network based
>tuners there exists a number of 3rd party
>tools to wait for the device(s) to come
>online.

To get systemd to make mythbackend wait for DVB tuners, do this:

root at mypvr:/etc/udev/rules.d# cat 99-tuner.rules
#
# Create systemd device units for capture devices
#
SUBSYSTEM=="video4linux", TAG+="systemd"
SUBSYSTEM=="dvb", TAG+="systemd"
SUBSYSTEM=="firewire", TAG+="systemd"

Create the above file as root, and chmod u=rw,og=r it.  The line that
matters is the dvb one - the other two are probably historical now.

Then in the systemd unit for mythbackend, add lines like these in the
[Unit] section:

Wants=dev-dvb-adapter0-frontend0.device
After=dev-dvb-adapter0-frontend0.device
Wants=dev-dvb-adapter1-frontend0.device
After=dev-dvb-adapter1-frontend0.device
Wants=dev-dvb-adapter2-frontend0.device
After=dev-dvb-adapter2-frontend0.device
Wants=dev-dvb-adapter3-frontend0.device
After=dev-dvb-adapter3-frontend0.device
Wants=dev-dvb-adapter4-frontend0.device
After=dev-dvb-adapter4-frontend0.device

I have 8 DVB-T2 tuners, of which 4 are used for mythbackend and one
for fetching MHEG5 EPG data externally for mythbackend.  The above
lines makes mythbackend wait for those 5 tuners to be present before
it is started.  You can manually create a
/etc/systemd/system/mythtv-backend.service.d/<any name>.conf file to
put them in, if you do not already have one.  Or these days, you can
just use this command:

sudo systemctl edit mythtv-backend

Then reboot.