linux-kernel - Re: [PATCH] ASoC: es8316: limit headphone mixer volume

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Date:   Mon, 26 Aug 2019 17:41:45 +0900
From:   Katsuhiro Suzuki <katsuhiro@...suster.net>
To:     Daniel Drake <drake@...lessm.com>,
        Hans de Goede <hdegoede@...hat.com>
Cc:     Mark Brown <broonie@...nel.org>,
        David Yang <yangxiaohua@...rest-semi.com>,
        alsa-devel@...a-project.org,
        Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ASoC: es8316: limit headphone mixer volume

Hello Daniel,

On 2019/08/26 11:53, Daniel Drake wrote:
> On Mon, Aug 26, 2019 at 1:38 AM Hans de Goede <hdegoede@...hat.com> wrote:
>> On 24-08-19 23:04, Katsuhiro Suzuki wrote:
>>> This patch limits Headphone mixer volume to 4 from 7.
>>> Because output sound suddenly becomes very loudly with many noise if
>>> set volume over 4.
> 
> That sounds like something that should be limited in UCM.
> 
>> Higher then 4 not working matches my experience, see this comment from
>> the UCM file: alsa-lib/src/conf/ucm/codecs/es8316/EnableSeq.conf :
>>
>> # Set HP mixer vol to -6 dB (4/7) louder does not work
>> cset "name='Headphone Mixer Volume' 4"
> 
> What does "does not work" mean more precisely?
> 
> I checked the spec, there is indeed something wrong in the kernel driver here.
> The db scale is not a simple scale as the kernel source suggests.
> 
> Instead it is:
> 0000 – -12dB
> 0001 – -10.5dB
> 0010 – -9dB
> 0011 – -7.5dB
> 0100 – -6dB
> 1000 – -4.5dB
> 1001 – -3dB
> 1010 – -1.5dB
> 1011 – 0dB
> 
 > So perhaps we can fix the kernel to follow this table and then use UCM
 > to limit the volume if its too high on a given platform?
 >

Thank you very important information. So you mean value 5, 6, 7 are
illegal settings for ES8316. Correct codes are

static const SNDRV_CTL_TLVD_DECLARE_DB_RANGE(hpmixer_gain_tlv,
	0, 4, TLV_DB_SCALE_ITEM(-1200, 150, 0),
	8, 11, TLV_DB_SCALE_ITEM(-450, 150, 0),
);

and...

	SOC_DOUBLE_TLV("Headphone Mixer Volume", ES8316_HPMIX_VOL,
		       0, 4, 15, 0, hpmixer_gain_tlv),

Is my understanding correct? If so I'll test it on my board
(RockPro64) and re-send patch.

BTW, do you know how to get ES8316 I2C registers spec?
I want to see it for understanding current code, but I cannot find...


> Thanks
> Daniel
> 
> 

Best Regards,
Katsuhiro Suzuki