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

[Takashi Iwai]

At Mon, 12 Dec 2011 11:55:59 -0200,
Gustavo Maciel Dias Vieira wrote:
> 
> Em Seg, 2011-12-12 às 12:27 +0100, Takashi Iwai escreveu:
> > At Sun, 04 Dec 2011 15:13:29 -0200,
> > Gustavo Maciel Dias Vieira wrote:
> > > 
> > > At least two HP laptop models with the IDT 92HD81B1X5 codec have the
> > > polarity of the mute led inverted with respect to the current driver
> > > default. Change the polarity for these machines only.
> > > 
> > > Signed-off-by: Gustavo Maciel Dias Vieira <gustavo at sagui.org>
> > 
> > Don't these have really no proper DMI entries?  The recent HP laptops
> > should have the mute LED GPIO pin and polarity set in SMBIOS. 
> 
> 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.

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.


thanks,

Takashi