[alsa-devel] cmipci CM_FLINKOFF disables multinchannel playback

Timofei V. Bondarenko tim at ipi.ac.ru
Mon Oct 29 18:01:40 CET 2007

Clemens Ladisch wrote:
> Timofei V. Bondarenko wrote:
>> I found the latest cmipci driver cannot playback in multichannel mode 
>> anymore.
>> My hardware is 'CMI8738 model 55' attempting to play 2 or 4 channels 
>> through the 2nd DAC i get no sound at all. 6 ch produces sound only at 
>> center/bass while front and rear still mute.
>> I found the root of problem in redefinition of some bits of the 
>> CM_REG_MISC_CTRL (0x18) register.
>> Was: CM_FLINKON=0x40, CM_FLINKOFF=0x20
>> Now it is: CM_FLINKON=0x80 CM_FLINKOFF=0x40
>> Note the CM_FLINKOFF does collide with the CM_MUTECH1=0x40 bit.
>> This bit disables playback on 2nd DAC.
>> The CM_FLINKOFF/CM_FLINKON bits used in the 'Modem' mixer control only.
>> During startup the mixer turns the modem off somewhere and this disables
>> 2nd DAC as well.
>> Complete removal of this 'Modem' control fixes the problem.
> Do you have any information about the exact chip version where this
> change happened?  It appears chip versions 39 and newer don't have
> a modem.

No. I'm talking not about chip versions.

The definitions was changed in the cmipci driver code.
In the patch named 'cmipci: update register definitions' about 18th 

My card certainly have no modem.

But the driver creates almost dummy 'Modem' control.
I suggested to remove it just because i see no use of this control other 
than flipping 2 bits in CM_REG_MISC_CTRL.


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