From: Mark Brown <broonie@kernel.org>
To: "Andrew F. Davis" <afd@ti.com>
Cc: Liam Girdwood <lgirdwood@gmail.com>,
Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
alsa-devel@alsa-project.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] ASoC: tlv320aic31xx: Add MICBIAS off setting
Date: Tue, 4 Sep 2018 16:56:55 +0100 [thread overview]
Message-ID: <20180904155655.GJ12993@sirena.org.uk> (raw)
In-Reply-To: <85973bf4-1acb-1731-d93e-29c8141a3c53@ti.com>
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On Tue, Sep 04, 2018 at 10:10:24AM -0500, Andrew F. Davis wrote:
> On 09/04/2018 09:55 AM, Mark Brown wrote:
> > you get to keep the pieces" territory. If we really want to have a way
> > of explicitly specifying that some widgets should never be turned on
> > then it feels like rather than have something device and widget specific
> > like this we should instead have a higher level way of doing that which
> > can be applied to any widget, that is something that could be useful
> > especially with things like speaker drivers where there's real potential
> > for physical damage to the system.
> Not sure how that could even look, it would need to be in DT as only
> that layer knows the connections, but then the it would also have to
> have internal knowledge of the widgets used in the driver..
We already have a bunch of DT code that knows about and uses the
external widgets the device has (which are I'd guess the only ones where
this is an issue)? I was thinking just have a property that lists the
widgets that should never be turned on.
> > Like I said in my original reply I'm also worried that this will break
> > existing boards by causing them to change to a voltage of 0 when they
> > had managed to end up with the default of 2V which happened to work for
> > them.
> Then only time this could happen is if they specified MICBIAS_OFF in DT
> but got the default 2v instead. In which case, yes, the behavior would
> change, but it would also be changing to the correct behavior. We can't
> avoid fixing code on the off chance someone depended on the broken
> behavior, no progress could ever be made.
I'm really having a lot of trouble seeing MICBIAS_OFF as a useful
voltage to specify in DT in the first place.
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next prev parent reply other threads:[~2018-09-04 15:57 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-31 18:05 [PATCH] ASoC: tlv320aic31xx: Add MICBIAS off setting Andrew F. Davis
2018-09-03 11:26 ` Mark Brown
2018-09-04 13:55 ` Andrew F. Davis
2018-09-04 14:41 ` Mark Brown
2018-09-04 14:43 ` Andrew F. Davis
2018-09-04 14:55 ` Mark Brown
2018-09-04 15:10 ` Andrew F. Davis
2018-09-04 15:56 ` Mark Brown [this message]
2018-09-04 16:02 ` Andrew F. Davis
2018-09-04 16:21 ` Mark Brown
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