Re: [RFC PATCH 2/5] HACK: ASoC: Add card->filter_controls hook

From: Mark Brown <broonie@kernel.org>
To: "Martin Povišer" <povik+lin@cutebit.org>
Cc: devicetree@vger.kernel.org, alsa-devel@alsa-project.org,
	Sven Peter <sven@svenpeter.dev>,
	linux-kernel@vger.kernel.org, Hector Martin <marcan@marcan.st>,
	Takashi Iwai <tiwai@suse.com>,
	Liam Girdwood <lgirdwood@gmail.com>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Kettenis <kettenis@openbsd.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>
Subject: Re: [RFC PATCH 2/5] HACK: ASoC: Add card->filter_controls hook
Date: Thu, 31 Mar 2022 12:34:29 +0100	[thread overview]
Message-ID: <YkWRxWjQSnJ9f281@sirena.org.uk> (raw)
In-Reply-To: <20220331000449.41062-3-povik+lin@cutebit.org>

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On Thu, Mar 31, 2022 at 02:04:46AM +0200, Martin Povišer wrote:

> Add a new ASoC card callback for filtering the kcontrols of the card's
> constituent components. This lets the card take over some of the
> controls, deciding their value instead of leaving it up to userspace.

Define "filter".  What is this trying to accomplish?  As a matter of
policy we don't put use case configuration in the kernel, the goal is to
avoid having to update the kernel when people decide to do new things
with their userspace.

> Also, and here's the HACK: part, move dapm_new_widgets call in front
> of the card's late_probe call. This way all kcontrols should have been
> created (and are safe to use) by the time late_probe is called.

This will break any card that adds new controls, you could add a second
call earlier but deleting the existing call is going to break other
users.

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