From: Sergej Sawazki <ce3a@gmx.de>
To: Takashi Iwai <tiwai@suse.de>, Clemens Ladisch <clemens@ladisch.de>
Cc: alsa-devel@alsa-project.org
Subject: Re: ASoC: How to declare volume TLV dB scale?
Date: Sat, 13 Jun 2015 12:10:05 +0200 [thread overview]
Message-ID: <557C017D.5090604@gmx.de> (raw)
In-Reply-To: <s5hioas5ba2.wl-tiwai@suse.de>
On Sat, 13 Jun 2015 09:15:49 +0200, Takashi Iwai wrote:
> At Fri, 12 Jun 2015 21:47:46 +0200,
> Clemens Ladisch wrote:
>>
>> Sergej Sawazki wrote:
>>>
>>> The output of the DAC can be attenuated in 0.125dB steps, so 0x200
>>> would be -64dB.
>>
>> 0.125 dB is too small for the 0.01 dB resolution of DECLARE_TLV_DB_SCALE,
>> so you have to use DB_MINMAX instead: TLV_DB_MINMAX_MUTE_ITEM(-128, 0)
>
> And you need to implement the ctl get/put callback to revert the value
> as (0x3ff - raw value). An decrement value isn't supposed to work.
>
Clemens, Takashi, thanks for your answers.
I am getting the expected dB scaling with:
DECLARE_TLV_DB_MINMAX_MUTE(vol_tlv, -12800, 0)
does it make sense?
Regards,
Sergej
next prev parent reply other threads:[~2015-06-13 10:10 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-12 12:02 ASoC: How to declare volume TLV dB scale? Sergej Sawazki
2015-06-12 16:28 ` Clemens Ladisch
2015-06-12 19:26 ` Sergej Sawazki
2015-06-12 19:47 ` Clemens Ladisch
2015-06-13 7:15 ` Takashi Iwai
2015-06-13 10:10 ` Sergej Sawazki [this message]
2015-06-13 10:29 ` Clemens Ladisch
2015-06-13 10:45 ` Sergej Sawazki
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