[alsa-devel] [snd-bt87x]: seems cannot powerup after powerdown...

Takashi Iwai tiwai at suse.de
Tue Aug 19 12:53:54 CEST 2008

Added Clemens and alsa-devel to Cc.

At Mon, 18 Aug 2008 19:22:20 +0400,
Dmitry Butskoy wrote:
> Hi,
> Recently snd-bt87x driver has started to use CTL_A_PWRDN bit, see
> http://git.kernel.org/?p=linux/kernel/git/stable/linux-2.6.26.y.git;a=commitdiff;h=950fb626dc28e17ae4ad01dba07957bdc6e0b997
> Unfortunately, it produces a regression, at least in my case.
> I have "AVerMedia TVPhone 98" card, lspci is:
> > 03:05.0 Multimedia video controller: Brooktree Corporation Bt878 Video 
> > Capture (rev 11)
> > 03:05.1 Multimedia controller: Brooktree Corporation Bt878 Audio 
> > Capture (rev 11)
> My card has no additional chip for digital sound, hence only analog is 
> available.
> After upgrading from 2.6.23 to 2.6.25, I have discovered no more sound 
> from my snd-bt87x device. Considering the code changes in the dirver, 
> I've guessed that it could be some power issues.
> Compiling the newest driver without CTL_A_PWRDN (ie. with that changes 
> reverted back) I got the sound back again.
> Note, that it is not enough to rmmod the old module and insmod the new. 
> I have to reboot computer completely with the new driver to take changes 
> in effect.

This is a nasty problem.  Reloading the module doesn't fix means that
the PCI enable/disable process also doesn't suffice...

Do you see any difference in PCI register space between the fresh boot
and the silent state?



> I can perform any tests, debug etc. if needed.
> Regards,
> Dmitry Butskoy
> http://www.fedoraproject.org/wiki/DmitryButskoy

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