Re: [BUG] Patch "CPU hotplug: call check_tsc_sync_source() with irqs off" breaks some drivers

[Nicolas Boichat <nicolas@boichat.ch>]

Nicolas Boichat wrote:
> Hello,
> 
> I'm running a Macbook Pro first generation (Core Duo, so x86).
> 
> I ran accross these two problems while upgrading from 2.6.21-rc3 to the
> current git HEAD:
>  1. appletouch cannot initialize the device properly at boot time (the
> module is automatically loaded by Gentoo), I have to reload the module
> to get it to work.
>  2. ALSA hda_intel (patch_sigmatel) fails to read properly the subsystem
> id. "head  /proc/asound/card0/codec#0" returns:
>> Codec: SigmaTel STAC9221 A1
>> Address: 0
>> Vendor Id: 0x83847680
>> Subsystem Id: 0x100
>> Revision Id: 0x103401
> while I expect this subsystem id: 0x106b0200.
> This is due to a read failure in sound/pci/hda/hda_codec.c at line 553
> (I have to reboot on OS X to get the id correct again, and it seems to
> happen quite randomly, so I'm not absolutely certain this bug is
> related, but it's something i have never seen before...)
> 
> I found out which commit seems to cause these bugs:
> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=d04f41e35343f1d788551fd3f753f51794f4afcf
> 
> The latest GIT without this commit works fine, but doesn't with it.

Sorry about blaming this commit. The problems happen randomly (about 1
reboot over 2 is ok, at least with 2.6.21-rc4). I'll run more tests and
post the results later.

Best regards,

Nicolas