Re: [PATCH] wm8962: add a simple DMIC enable control

From: Charles Keepax <ckeepax@opensource.cirrus.com>
To: Martin Kepplinger <martin.kepplinger@puri.sm>
Cc: alsa-devel@alsa-project.org, kernel@puri.sm,
	patches@opensource.cirrus.com, tiwai@suse.com,
	lgirdwood@gmail.com, broonie@kernel.org, geert@glider.be,
	daniel.baluta@nxp.com
Subject: Re: [PATCH] wm8962: add a simple DMIC enable control
Date: Wed, 2 Feb 2022 13:35:11 +0000	[thread overview]
Message-ID: <20220202133511.GB18506@ediswmail.ad.cirrus.com> (raw)
In-Reply-To: <99b847d17e8ac399dba10842ec20091df926aa06.camel@puri.sm>

On Wed, Feb 02, 2022 at 12:55:04PM +0100, Martin Kepplinger wrote:
> Am Mittwoch, dem 02.02.2022 um 10:46 +0000 schrieb Charles Keepax:
> > On Wed, Feb 02, 2022 at 11:17:34AM +0100, Martin Kepplinger wrote:
> > > Am Mittwoch, dem 02.02.2022 um 09:53 +0000 schrieb Charles Keepax:
> > > > On Tue, Feb 01, 2022 at 04:01:13PM +0100, Martin Kepplinger
> > > > wrote:
> > > Do you have a code example from a different codec that has roughly
> > > what
> > > is missing here? (the sound subsystem is new to me)
> > 
> > Full disclosure this is complete untested, but it should be
> > pretty close. Let me know if it does the trick and I will send a
> > proper patch to the list. I do have a Librem 5 in a draw
> > somewhere so can pull that out if we get really stuck, but that
> > might have to wait until the weekend :-).
> > 
> > I don't know if you guys are using the analogue bypass paths
> > around the digital core on the chip. I think those will still
> > work with the mics set to digital, so I have left the routes as
> > is, but that might require some checking at some point.
> 
> ok that's great and seems to work! that's luxury.
> 

Excellent glad that is working for you, I will prep up a proper
patch and send it to the list. Should get that done tomorrow
morning, if I don't manage it this afternoon.

> Volume / sensitivity of Analog input is too low, I saw that before.
> What would you try to change that?
> 

Hmm... you say you saw this before? I assume the input volume
is always low, not just low sometimes? I would probably start by
checking the voltage you have on the micbias, make sure that is
as expected. Does the signal coming into the IN3R pin look low on
a scope or is it just the level after it has been through the ADC
on the chip that seems low?

The input routing on this chip is pretty byzantine, the output of
just "amixer" showing all the controls in the relevant use-case
would probably be helpful to look over. I suspect there is a
reasonable chance something around the input PGA is not
configured to match the hardware, although I am not the most
familiar with this part so hard to guess at exactly what off the
top of my head.

Finally, do you know how much the amplitude is off by?

> you can do all of our tasks if you want to :)
> 

Ha! Not sure about that, but happy to help out where I can.

Thanks,
Charles