Alsa, ES1978 Maestro 2E

 · Jean Schurger

A while ago I had an Toshiba laptop and some issue with the sound card.

Just quoting from:

I have an (old) laptop with an ESS Technology ES1978 Maestro 2E
rev 10), that seems to have an "STAC9721/23" inside (id =

0000:00:08.0 Multimedia audio controller: ESS Technology ES1978 Maestro
2E (rev 10)
Subsystem: Dell: Unknown device 00aa
Flags: bus master, medium devsel, latency 32, IRQ 5
I/O ports at d800 [size=256]
Capabilities: [c0] Power Management
version 2

in the snd_ac97_mixer() function,  the ac97 driver test the
AC97_REC_GAIN register by writing 0x8a06 on it, and if it read
well the same value, it enable the AC97_SCAP_AUDIO.

But, on my board, the last quartet of AC97_REC_GAIN, is always
readen as 0, then when the AC97_REC_GAIN is tested, it return
0x0a06 instead of 0x8a06, and the ac97 driver tell "(not audio
or modem codec)", then no sound card.

I simply added a test of 0x83847609 to |= 0x8000 to the test
value, and all works fine.