[Linux-kernel-mentees] modprobing 'vidtv' doesn't really do anything

Daniel W. S. Almeida dwlsalmeida at gmail.com
Sat May 16 22:09:35 UTC 2020

Hi Mauro!

I am trying to iron out the bugs in the virtual DVB driver I have been
working on for the past few months.

modprobing vidtv_bridge apparently works, i.e. 'vidtv_bridge' gets
listed in the output of 'lsmod' and there's a message on dmesg warning
against loading out of tree modules.

It does not seem like the probe function actually runs, though. I have
added a printk call in vidtv_bridge_i2c_probe() but it does not output
anything to dmesg.

Also, I am using QEMU + KGDB and the debugger does not break into this
function (or into any other function in vidtv_bridg.c) at all, although
it can actually get the addresses for them, i.e.

4       breakpoint     keep y   0xffffffffc0000025 in
vidtv_bridge_i2c_probe at drivers/media/test-drivers/vidtv/vidtv_bridg.c:373
5       breakpoint     keep y   0xffffffffc0000523 in
vidtv_bridge_i2c_remove at drivers/media/test-drivers/vidtv/vidtv_bridg.c:416

It can't find these, though:
2       breakpoint     keep y   <PENDING>          drivers/media/test-drivers/vidtv/vidtv_bridg.c:vidtv_bridge_driver_exit
3       breakpoint     keep y   <PENDING>          drivers/media/test-drivers/vidtv/vidtv_bridg.c:vidtv_bridge_driver_init

>The best is to start using dvbv5 tools inside v4l-utils.
>The first step to check if the demod code was properly loaded is to run:
>$ dvb-fe-tool 

I tried this, but to no avail.
>WARNING device dvb0.frontend0 not found

I am stuck, can I get some help with this issue?



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