[alsa-devel] [PATCH 1/2] ALSA: ASoC: add STA32X codec driver

[Lars-Peter Clausen]

On 06/15/2011 10:53 PM, Johannes Stezenbach wrote:
> On Wed, Jun 15, 2011 at 04:05:16PM +0100, Mark Brown wrote:
>> On Tue, Jun 14, 2011 at 09:27:05PM +0200, Daniel Mack wrote:
>>
>>> +static const char *sta32x_limiter_ac_release_thr[] = {
>>> +	"-inf", "-29dB", "-20dB", "-16dB", "-14dB", "-12dB", "-10dB", "-8dB",
>>> +	"-7dB", "-6dB", "-5dB", "-4dB", "-3dB", "-2dB", "-1dB", "0dB" };
>>> +static const char *sta32x_limiter_drc_attack_thr[] = {
>>> +	"-31dB", "-29dB", "-27dB", "-25dB", "-23dB", "-21dB", "-19dB", "-17dB",
>>> +	"-16dB", "-15dB", "-14dB", "-13dB", "-12dB", "-10dB", "-7dB", "-4dB" };
>>> +static const char *sta32x_limiter_drc_release_thr[] = {
>>> +	"-inf", "-38dB", "-36dB", "-33dB", "-31dB", "-30dB", "-28dB", "-26dB",
>>> +	"-24dB", "-22dB", "-20dB", "-18dB", "-15dB", "-12dB", "-9dB", "-6dB" };
>>> +
>>
>> Doing these as regular volume TLVs will tend to work better in UIs.
> 
> The steps are not evenly distributed so I thought this is the
> only way to describe the hardware correctly.  Or is there a
> way to do controls which look like a slider in alsamixer
> with steps as shown above?
> 

You can put multiple scale items each with their own min/max value into a TLV.
For example for DRC attack in your case this would look like:

static const unsigned int drc_attack_tlv[] = {
	TLV_DB_RANGE_HEAD(3),
	0, 7, TLV_DB_SCALE_ITEM(-3100, 200, 0),
	8, 13, TLV_DB_SCALE_ITEM(-1600, 100, 0),
	14, 16, TLV_DB_SCALE_ITEM(-1000, 300, 0),
};

- Lars