Re: [REGRESSION bisected] Sound goes too fast due to commit 7b3a177b0

[Takashi Iwai <tiwai@suse.de>]

At Thu, 15 Apr 2010 23:19:33 +0200,
Éric Piel wrote:
> 
> Op 14-04-10 18:01, Takashi Iwai schreef:
> :
> >>
> >> I don't fully grasp the meaning of bdl_pos_adj, so I don't know if it's
> >> a bug to not play correctly when forcing it to 0. Is it?
> > 
> > It might be that this was for reducing the load by position
> > correction mechanism.  You might see the hd-audio kernel thread in a
> > high CPU usage.  This might be fixed also by position_fix=1, though. 
> Yes, I had added this option after a regression in the previous kernel
> which causes the hd-audio thread to take 50% of a CPU. Eventually, it
> was fixed and not needed anymore. So I guess in the case of my laptop,
> this is not really a regression, because everything is fine with the
> default values.
> 
> In the case of Frank, this looks more like a regression, or at least a
> bug to solve, because this happens with the default options. However,
> this report should be taken with care, because this happens on a
> 2.6.33.2 kernel made by Mandriva, containing many alsa patches of
> 2.6.34. Frank, how possible would it be to test a 2.6.34-rc4 kernel from
> Linus?
> 
> If this bug is confirmed, Takashi, do you know any way to choose
> automatically position_fix=1 when needed?

There is a quirk table in sound/pci/hda_intel.c to check PCI SSID.
I already added an entry for Frank's machine on sound git tree which
will be included in the pull request I'm going to send soon.
(Sorry the mail went outside since Frank's reply was private.)


thanks,

Takashi