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[SOLVED] No /dev/dvb entry for usb tuner
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g99
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Joined: 12 Jun 2007
Posts: 32

PostPosted: Sun Feb 01, 2015 11:15 am    Post subject: [SOLVED] No /dev/dvb entry for usb tuner Reply with quote

Hi all,

I have a Delock 61959 dvb tuner (version 1 which is supported by v4l-dvb). It used to work with kernel 3.11.x or 3.12.x and stopped working since 3.16.x or so.

After upgrading the kernel I just follow the instructions described on the linuxtv wiki (http://www.linuxtv.org/wiki/index.php/How_to_Obtain,_Build_and_Install_V4L-DVB_Device_Drivers), restart my computer but no /dev/dvb entry is created.

On the other hand my dmesg output looks fine to me:
Code:
$ dmesg | grep em28xx
[    4.606736] em28xx: New device  USB 2875 Device @ 480 Mbps (1b80:e1cc, interface 0, class 0)
[    4.606738] em28xx: DVB interface 0 found: isoc
[    4.606791] em28xx: chip ID is em2874
[    4.876129] usbcore: registered new interface driver em28xx
[    4.951075] input: em28xx IR (em2874 #0) as /devices/pci0000:00/0000:00:1d.7/usb2/2-3/rc/rc0/input7
[    4.951120] rc0: em28xx IR (em2874 #0) as /devices/pci0000:00/0000:00:1d.7/usb2/2-3/rc/rc0
[    4.951532] em28xx: Registered (Em28xx Input Extension) extension

Here are my loaded kernel modules:
Code:
$ sudo lsmod
Module                  Size  Used by
rc_delock_61959         1073  0
em28xx_rc               8252  0
rc_core                16532  3 rc_delock_61959,em28xx_rc
em28xx                 69850  1 em28xx_rc
tveeprom               14713  1 em28xx
v4l2_common             2901  1 em28xx
videodev              124040  2 em28xx,v4l2_common
media                  11273  1 videodev
radeon               1391478  2
cfbfillrect             3786  1 radeon
cfbimgblt               2079  1 radeon
cfbcopyarea             3230  1 radeon
drm_kms_helper         61052  1 radeon
ttm                    59694  1 radeon

There are no new entries in the kernel config in the Device Drivers -> Multimedia support -> Media USB Adapters after I install the v4l-dvb drivers either, and I can't remember if there used to be before it stopped working.

Do you have any ideas if I'm doing something wrong or missing something important?

Thanks for your input in advance!


Last edited by g99 on Mon Feb 02, 2015 8:01 pm; edited 1 time in total
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Roman_Gruber
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Joined: 03 Oct 2006
Posts: 3806
Location: Austro Bavaria

PostPosted: Sun Feb 01, 2015 11:25 am    Post subject: Reply with quote

off-topic: You may stick to the long term supported 3.10.x kernel from kernel.org and save you the hassle.

you may make diff of the config files from the working and the newer kernels or
check the changelogs regarding your hardware.

Those general guides for hardwares are usually only valid for a certain kernel version until it is changed. I had it several times that settings moved in the kernel and sticking to a proven long term support keeps out such issues at all.

you may check if there is another entry created, maybe it was just renamed. HAvre you checked the kernel.org change log regarding your hardware?
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g99
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Joined: 12 Jun 2007
Posts: 32

PostPosted: Sun Feb 01, 2015 2:30 pm    Post subject: Reply with quote

I reinstalled the latest stable versions of kernel 3.10.x and 3.12.x from the repositories but there's still no /dev/dvb, and it's recognized according to the dmesg messages.

I haven't found anything in the kernel change logs regarding my device but the kernel in itself doesn't support it, that's why I have to install the v4l-dvb drivers. As the respective modules seem to get loaded correctly I assume the issue could be well related to udev, i.e. it doesn't load the device properly for some reason.
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chithanh
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Joined: 05 Aug 2006
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Location: Berlin, Germany

PostPosted: Mon Feb 02, 2015 1:11 am    Post subject: Reply with quote

The em28xx provides both analog and digital TV. If you want to use the digital part, you need to build the em28xx_dvb driver. Also you need to ensure that the DVB frontend in the device is supported too (Google says your device has a DRXK tuner).
.config:
CONFIG_VIDEO_EM28XX_DVB=m
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g99
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Joined: 12 Jun 2007
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PostPosted: Mon Feb 02, 2015 8:01 pm    Post subject: Reply with quote

chithanh wrote:
The em28xx provides both analog and digital TV. If you want to use the digital part, you need to build the em28xx_dvb driver. Also you need to ensure that the DVB frontend in the device is supported too (Google says your device has a DRXK tuner).
.config:
CONFIG_VIDEO_EM28XX_DVB=m


Hi chithanh,

I was able to solve the problem based on what you've written. Thank you very much :D

I searched for VIDEO_EM28XX_DVB in the menuconfig and found out that it had an option but it was hidden. I traced back its dependencies and it turns out you have to build one of these options into the kernel: MEDIA_CAMERA_SUPPORT, MEDIA_ANALOG_TV_SUPPORT, MEDIA_RADIO_SUPPORT, MEDIA_SDR_SUPPORT. I only had MEDIA_DIGITAL_TV_SUPPORT enabled so my driver was not visible.

It works like a charm now 8)
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