Template Based Coefficients Setting for Filters

Template Based Coefficients Setting for Filters

[Ashish Chavan]

Hi,
   I am working on updating ASoC codec driver for Dialog's DA7210 codec
(sound/soc/codec/da7210.c). This update would be a major functionality
update in nature. Currently, I am implementing support for GP (general
purpose) filters of this codec and need some opinions/comments.

Brief info about GP filters:

The additional general purpose (GP) filter engine offers up
to eight 2nd order biquad filter stages with freely
configurable 16 bit coefficients and supports flexible
digital audio routing and mixing arrangements.

This engine implements transfer function to derive Hz which uses five
coefficients, a1, a1, a2, b1 and b2. The coefficients are specified
as 16 bit twos-complement numbers. There are total eight blocks which
can be interconnected as per requirement. 

Total number of registers to configure = (5 * 2 * 8) = 80

The GP filters are mainly designed to be used for following modes,

(1) Stereo Playback
(2) Stereo Capture
(3) Capture with monitoring
(4) Spatializer mode
(5) Left-Sidetone filtering
(6) Right-Sidetone filtering
(7) Left-Right Sidetone filtering

Each of this mode requires different set of coefficients to be
programmed in to those 80 registers.

My idea of implementation:

I believe that it would be quite non practical(because of number of
controls required to do that) to provide individual control to set each
coefficient independently. What I am thinking is a virtual control named
something like, "GP Filter Mode Selection". It would offer above seven
options to user. On selection of any option, driver will populate that
set of 80 registers with predefined coefficients. It would be like
selecting one out of seven predefined templates.

(Apart from the coefficients part, some interconnections between these
blocks and IOs need to be done to achieve desired mode.)

Is this a good/valid way to handle this? Is there any alternative?

Thanks,

-- Ashish

Re: Template Based Coefficients Setting for Filters

[Mark Brown]

On Tue, Aug 09, 2011 at 06:03:56PM +0530, Ashish Chavan wrote:

>    I am working on updating ASoC codec driver for Dialog's DA7210 codec
> (sound/soc/codec/da7210.c). This update would be a major functionality
> update in nature. Currently, I am implementing support for GP (general
> purpose) filters of this codec and need some opinions/comments.

Use _BYTES controls for this.  There are no existing users in ASoC,
though there should be shortly and there are generic ALSA examples.

Re: Template Based Coefficients Setting for Filters

[Steve Calfee]

On 08/09/11 08:16, Mark Brown wrote:
> On Tue, Aug 09, 2011 at 06:03:56PM +0530, Ashish Chavan wrote:
> 
>>    I am working on updating ASoC codec driver for Dialog's DA7210 codec
>> (sound/soc/codec/da7210.c). This update would be a major functionality
>> update in nature. Currently, I am implementing support for GP (general
>> purpose) filters of this codec and need some opinions/comments.
> 
> Use _BYTES controls for this.  There are no existing users in ASoC,
> though there should be shortly and there are generic ALSA examples.

Hi Mark,

Could you expand on this. Neither google or lxr found anything about
_BYTES controls. Where is it defined in the source?

Regards, Steve

Re: Template Based Coefficients Setting for Filters

[Johannes Stezenbach]

(add back Cc:s)

Hi Steve,

On Tue, Aug 09, 2011 at 10:19:27AM -0700, Steve Calfee wrote:
> On 08/09/11 08:16, Mark Brown wrote:
> > On Tue, Aug 09, 2011 at 06:03:56PM +0530, Ashish Chavan wrote:
> > 
> >>    I am working on updating ASoC codec driver for Dialog's DA7210 codec
> >> (sound/soc/codec/da7210.c). This update would be a major functionality
> >> update in nature. Currently, I am implementing support for GP (general
> >> purpose) filters of this codec and need some opinions/comments.
> > 
> > Use _BYTES controls for this.  There are no existing users in ASoC,
> > though there should be shortly and there are generic ALSA examples.
> 
> Hi Mark,
> 
> Could you expand on this. Neither google or lxr found anything about
> _BYTES controls. Where is it defined in the source?

I've written a driver for ST32x, it will be in 3.1.  My patch
to use _BYTES controls were posted here not long ago, see
http://thread.gmane.org/gmane.linux.alsa.devel/87063


HTH
Johannes

Re: Template Based Coefficients Setting for Filters

[Mark Brown]

On Tue, Aug 09, 2011 at 11:28:24PM +0200, Johannes Stezenbach wrote:
> On Tue, Aug 09, 2011 at 10:19:27AM -0700, Steve Calfee wrote:

> > Could you expand on this. Neither google or lxr found anything about
> > _BYTES controls. Where is it defined in the source?

> I've written a driver for ST32x, it will be in 3.1.  My patch
> to use _BYTES controls were posted here not long ago, see
> http://thread.gmane.org/gmane.linux.alsa.devel/87063

$ grep _BYTES include/sound/*.h sound/core/*.c

Re: Template Based Coefficients Setting for Filters

[Takashi Iwai]

At Wed, 10 Aug 2011 08:33:58 +0900,
Mark Brown wrote:
> 
> On Tue, Aug 09, 2011 at 11:28:24PM +0200, Johannes Stezenbach wrote:
> > On Tue, Aug 09, 2011 at 10:19:27AM -0700, Steve Calfee wrote:
> 
> > > Could you expand on this. Neither google or lxr found anything about
> > > _BYTES controls. Where is it defined in the source?
> 
> > I've written a driver for ST32x, it will be in 3.1.  My patch
> > to use _BYTES controls were posted here not long ago, see
> > http://thread.gmane.org/gmane.linux.alsa.devel/87063
> 
> $ grep _BYTES include/sound/*.h sound/core/*.c

Better use the power of git :)

% git grep SNDRV_CTL_ELEM_TYPE_BYTES
include/sound/asound.h:#define  SNDRV_CTL_ELEM_TYPE_BYTES       ((__force snd_ct
sound/core/control.c:   case SNDRV_CTL_ELEM_TYPE_BYTES:
sound/core/control_compat.c:    case SNDRV_CTL_ELEM_TYPE_BYTES:
sound/i2c/cs8427.c:     uinfo->type = SNDRV_CTL_ELEM_TYPE_BYTES;
sound/i2c/other/ak4113.c:       uinfo->type = SNDRV_CTL_ELEM_TYPE_BYTES;
sound/i2c/other/ak4114.c:       uinfo->type = SNDRV_CTL_ELEM_TYPE_BYTES;
sound/i2c/other/ak4117.c:       uinfo->type = SNDRV_CTL_ELEM_TYPE_BYTES;
sound/pci/ice1712/aureon.c:     uinfo->type = SNDRV_CTL_ELEM_TYPE_BYTES;
sound/pci/ice1712/ice1712.c:    uinfo->type = SNDRV_CTL_ELEM_TYPE_BYTES;
sound/pci/ice1712/ice1724.c:    uinfo->type = SNDRV_CTL_ELEM_TYPE_BYTES;
sound/soc/codecs/sta32x.c:      uinfo->type = SNDRV_CTL_ELEM_TYPE_BYTES;


Takashi

Re: Template Based Coefficients Setting for Filters

[Ashish Chavan]

On Tue, 2011-08-09 at 23:28 +0200, Johannes Stezenbach wrote:

> I've written a driver for ST32x, it will be in 3.1.  My patch
> to use _BYTES controls were posted here not long ago, see
> http://thread.gmane.org/gmane.linux.alsa.devel/87063
> 
Thanks for point the patch. It really helped.

Any idea about how this type of controls are used-via/represented-in
alsamixer?


-- Ashish