Re: [PATCH] ASoC: es8316: limit headphone mixer volume

[Katsuhiro Suzuki]

Hello Daniel,

On 2019/08/26 11:53, Daniel Drake wrote:
> On Mon, Aug 26, 2019 at 1:38 AM Hans de Goede <hdegoede@xxxxxxxxxx> 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 â -12dB
> 0001 â -10.5dB
> 0010 â -9dB
> 0011 â -7.5dB
> 0100 â -6dB
> 1000 â -4.5dB
> 1001 â -3dB
> 1010 â -1.5dB
> 1011 â 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