[alsa-devel] [PATCH] ALSA: hda: invert mute led polarity for HP laptops

[Takashi Iwai]

At Mon, 12 Dec 2011 14:07:50 -0200,
Gustavo Maciel Dias Vieira wrote:
> 
> Em Seg, 2011-12-12 às 15:04 +0100, Takashi Iwai escreveu:
> > At Mon, 12 Dec 2011 11:55:59 -0200,
> > Gustavo Maciel Dias Vieira wrote:
> > > Unfortunately no. Actually, it appears someone at HP is pulling a
> > prank
> > > on us. In a Pavilion dm4 the BIOS string is "HP_Mute_LED_P_G", where
> > P
> > > and G are not numbers, but the actual letters.
> > 
> > Doh, they forgot to fill the right numbers there.  Obviously a BIOS
> > bug.
> > 
> > For such machines, the IDs should be explicitly checked instead of
> > marking all machines with this codec.  That is, the influence must be
> > as small as possible.  Or, just check "HP_Mute_LED_P_G" string as an
> > identifier of bad machines, and apply a special handling.
> 
> I can do both, to be double sure. Just tell me which ID to use. I
> assumed that codec->subsystem_id was unique enough (by inspecting
> hp_blike_system(u32))

Yes, subsytem_id can be used.  OTOH, I guess HP_Mute_LED_P_G check
would be easier and may cover more machines.  So, I prefer the
latter.

> > BTW, now IDT guys and I are discussing about dropping the fallback
> > case for 92HD83x codecs because it can break potentially the EAPD.
> > Your patch won't work any more if that change is applied.  So, a more
> > solid fix would be needed anyway.
> 
> It's a BIOS bug. Any fix is going to suck. :)

Yeah, but we try to keep less damage by the suck :)


thanks,

Takashi