Re: Conflict between v4l and adi module

From: Scott Bronson (
Date: Tue Jul 31 2001 - 11:01:02 EST

> > Immediately after booting, if I fire up my BT848-based TV
> > tuner, quit, then try to open /dev/js0, [it fails].
> Can you confirm by strace that the open() fails ?


open("/lib/", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\210\324"..., 1024) = 1024
fstat64(3, {st_mode=S_IFREG|0755, st_size=1149960, ...}) = 0
old_mmap(NULL, 1166404, PROT_READ|PROT_EXEC, MAP_PRIVATE, 3, 0) = 0x40025000
mprotect(0x40138000, 40004, PROT_NONE) = 0
old_mmap(0x40138000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 0x112000) = 0x40138000
old_mmap(0x4013e000, 15428, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x4013e000
close(3) = 0
munmap(0x40016000, 59758) = 0
getpid() = 665
open("/dev/js0", O_RDONLY) = -1 ENODEV (No such device)
write(2, "jstest: No such device\n", 23jstest: No such device
) = 23
_exit(1) = ?

>> [after rmmoding and modprobing adi]
> Can you confirm that it actually works as opposed to open() working ?
> Does it produce correct values ?

Yes, open() now works and it also produces correct values.
It will continue to work, even if I use v4l again, until
I reboot.

> Do you know whether this occurs with all joysticks ?

Alas, I don't know. I'd especially like to know if USB joysticks
work like this. Maybe somebody else on this list could try to
reproduce the problem.

> Do you use your soundcard the joystick is attached to to play sound from
> the TV card ?

Nope. It goes to some dedicated $5 computer speakers. The v4l-based
webcams that also cause this problem don't have any audio either.
That was a good thought, but I'm pretty sure it's not audio related.

> Could you try compiling the joystick drivers into the kernel ?

Sure. It didn't change anything. /dev/jso: No such device. However,
now I can't rmmod and insmod adi to fix it. :)

        - Scott

> > To summarize, the failure (/dev/js0: No such device) only happens
> > if I use v4l before opening /dev/js0 after booting the computer.
> > Once /dev/js0 is successfully opened, it always works from then on.
> > rmmoding and insmoding adi always resolves the conflict. Rebooting
> > and then using v4l before opening the joystick always causes it.
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This archive was generated by hypermail 2b29 : Tue Jul 31 2001 - 21:00:51 EST