Subject: Re: mod to the ess driver?
To: Brett Lymn <>
From: Nathan J. Williams <nathanw@MIT.EDU>
List: current-users
Date: 09/11/2000 11:24:38
<> (Brett Lymn) writes:

>         I have a Digital HiNote Ultra II laptop which has an ess sound
> chip in it.  The ess driver probes it as a ess1788 chip but the probe
> bombs out complaining it cannot set a bit in a register.  I tracked
> this down in the driver and, just for kicks, made the error
> non-fatal.  Doing this made the sound work, where the value of work is
> "can play mp3's @ 44.1k in stereo".  

Please test recording as well.

> I cannot find any useful documentation on the ess chips (what I
> found on the web site was more a hardware style app note) so I
> cannot say what "bit 2" does or does not do for me.  Would it be
> valid to just make the test a non-fatal error in the probe?  Has
> anyone got the register documentation for this chip? (or know where
> I can get it)

I have the ESS-1788 manual; it's only avaliable in dead-tree form, and
a little annoying to find the person who will send you a copy.

But anyway, bit 2 of mixer register 0x64 is:

"Bit 2: 1: Enable H/W volume interrupt request to use IRQE
 (potentially sharing with MPU-401)"

It's not a crucial bit, certainly. We don't use the volume interrupt,
and that toggling in ess_identify() doesn't seem like it really helps
identifying an ESS chip (at that point we've already done a successful
reset and read of the ID register). I do wonder why it doesn't work, though.

If we can't figure out what that probe is good for, it should probably
just be removed.

        - Nathan