limitations on number of alsa controls for a card

limitations on number of alsa controls for a card

[Vinod Koul]

Hi,

Is there any limitation on maximum number of controls we can have.

I had some platform side controls to represent DSP and adding them made
some of codec controls to vanish. And looks like if I register these
platform controls not all codec controls are visible in userpsace.
Is there nay max limit I am hitting?

-- 
~Vinod

Re: limitations on number of alsa controls for a card

[Mark Brown]

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On Wed, Oct 31, 2012 at 07:37:31PM +0530, Vinod Koul wrote:

> Is there any limitation on maximum number of controls we can have.

> I had some platform side controls to represent DSP and adding them made
> some of codec controls to vanish. And looks like if I register these
> platform controls not all codec controls are visible in userpsace.
> Is there nay max limit I am hitting?

Not that I'm aware of beyond sizeof() type stuff which you're probably
still a way away from.  How are you listing the controls and are there
any name collisons?

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Re: limitations on number of alsa controls for a card

[Vinod Koul]

On Thu, 2012-11-01 at 14:25 +0000, Mark Brown wrote:
> On Wed, Oct 31, 2012 at 07:37:31PM +0530, Vinod Koul wrote:
> 
> > Is there any limitation on maximum number of controls we can have.
> 
> > I had some platform side controls to represent DSP and adding them made
> > some of codec controls to vanish. And looks like if I register these
> > platform controls not all codec controls are visible in userpsace.
> > Is there nay max limit I am hitting?
> 
> Not that I'm aware of beyond sizeof() type stuff which you're probably
> still a way away from.  How are you listing the controls and are there
> any name collisons?
alsa_amixer -c"cardname" controls

if there isn't anything in kernel which limits this, would there be
something in alsa-lib to have this kind of behavior?

-- 
~Vinod

Re: limitations on number of alsa controls for a card

[Felix Homann]

2012/11/1 Vinod Koul <vinod.koul@linux.intel.com>:
> On Thu, 2012-11-01 at 14:25 +0000, Mark Brown wrote:
>> On Wed, Oct 31, 2012 at 07:37:31PM +0530, Vinod Koul wrote:
>>
>> > Is there any limitation on maximum number of controls we can have.
>>
>>
>> Not that I'm aware of beyond sizeof() type stuff which you're probably
>> still a way away from.

At least, for USB devices there's a maximum for logical mixer channels
(currently, MAX_CHANNELS = 16).  This might feel like a limit for the
number of mixer controls depending on the respective mixer topoplogy.
MAX_CHANNELS can't be raised deliberately in the current code since it
is used for some bitshifting. I don't know if something similar exists
for PCI devices

Re: limitations on number of alsa controls for a card

[Raymond Yau]

2012-11-1 下午11:01 於 "Vinod Koul" <vinod.koul@linux.intel.com> 寫道：
>
> On Thu, 2012-11-01 at 14:25 +0000, Mark Brown wrote:
> > On Wed, Oct 31, 2012 at 07:37:31PM +0530, Vinod Koul wrote:
> >
> > > Is there any limitation on maximum number of controls we can have.
> >
> > > I had some platform side controls to represent DSP and adding them
made
> > > some of codec controls to vanish. And looks like if I register these
> > > platform controls not all codec controls are visible in userpsace.
> > > Is there nay max limit I am hitting?
> >
> > Not that I'm aware of beyond sizeof() type stuff which you're probably
> > still a way away from.  How are you listing the controls and are there
> > any name collisons?
> alsa_amixer -c"cardname" controls
>
> if there isn't anything in kernel which limits this, would there be
> something in alsa-lib to have this kind of behavior?
>
> --

those inactive controls are not listed by amixer

try alsactl store -f foo.state
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Re: limitations on number of alsa controls for a card

[Takashi Iwai]

At Thu, 01 Nov 2012 20:16:51 +0530,
Vinod Koul wrote:
> 
> On Thu, 2012-11-01 at 14:25 +0000, Mark Brown wrote:
> > On Wed, Oct 31, 2012 at 07:37:31PM +0530, Vinod Koul wrote:
> > 
> > > Is there any limitation on maximum number of controls we can have.
> > 
> > > I had some platform side controls to represent DSP and adding them made
> > > some of codec controls to vanish. And looks like if I register these
> > > platform controls not all codec controls are visible in userpsace.
> > > Is there nay max limit I am hitting?
> > 
> > Not that I'm aware of beyond sizeof() type stuff which you're probably
> > still a way away from.  How are you listing the controls and are there
> > any name collisons?
> alsa_amixer -c"cardname" controls

Better to use alsactl for obtaining the list of raw control elements.

> if there isn't anything in kernel which limits this, would there be
> something in alsa-lib to have this kind of behavior?

In most cases, such a problem is a driver bug, e.g. creating control
elements conflicting with each other for the mixer abstraction.


Takashi