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

[Katsuhiro Suzuki]

Hello Hans, Daniel,

Thank you for reviewing and comment.

On 2019/08/26 18:09, Hans de Goede wrote:
> Hi,
>
> On 26-08-19 04:53, 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?
>
> IIRC garbled sound.
>
> > 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?
>
> Yes that sounds like the right thing to do. Katsuhiro can you confirm that
> using this table allows using the full scale ? note that the full scale now
> has 9 steps rather then 8.

I've finished testing this table on my board (RockPro64).
Every values work well without garbled sound.

I checked address 0x16 register via /sys/kernel/debug/regmap too.
The register values and dB (get from alsamixer) are the following if
I increase headphone volume to max from min.

  reg   dB
  0x16  scale
  ------------
  0x00  -12.00
  0x11  -10.50
  0x22  -9.00
  0x33  -7.50
  0x44  -6.00
  0x88  -4.50
  0x99  -3.00
  0xaa  -1.50
  0xbb  0.00


And I found other problem, current code is inverted L/R volume.
It's only in Headphone "mixer" volume. It seems Headphone "master"
volume works correctly.

I'll fix these problems and send V2 patch set.


> Regards,
>
> Hans

Best Regards,
Katsuhiro Suzuki