From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5117B37EFFF; Fri, 10 Apr 2026 10:28:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775816935; cv=none; b=LKrCPHtsXKjBLMVQi0IO6jcrKc1jU30kIYrS6l1uk5G/JZRCetMZgBoxj+7EBAgQL0uAJ4EN6tJgAbvvKEOYKtBb29EBgUpgOUQSSW5KuUN8es7dXp3VdoOQdqc00ZKtbEXx1TqN9b9eGTF0mRgFafUy6LtuytxEE66AIQ7R2W4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775816935; c=relaxed/simple; bh=JcpXPHlj5lb/tC6GGA8d4uK2G8UACazbeyqXotcuMjs=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=q6/s03Eni1EFaW2IMW0cjI2OA4Vwj1IejUKc9bY5+FdxqGfRNh6bu8hk2Uxrs9aoRtlBGu0Xc8KvaQ4zPOcqAKKMaKckNKAQlthU1JIGYMo5tOhSLDvqKkYHfRPo1fVHNIS6G49W4qDRwuJZWw4exxTPC7cvIaJfz4QAXSWqhCI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Sm0Jn21W; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Sm0Jn21W" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A05F8C19421; Fri, 10 Apr 2026 10:28:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1775816934; bh=JcpXPHlj5lb/tC6GGA8d4uK2G8UACazbeyqXotcuMjs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Sm0Jn21W5KKuhJBrMB+l4yidD3bcufvSGT8Fdnj+KnFoTrB3fMBJS9QZC8b+sBcFN JiVbKkbdTZnLQqYsvw53QhRdiUWcYP9R97Na7ijJDAUSduZJk1DScVeIxG03n47Nch XPaV4Q7FDC4gP9TiIJ7GNtZt2DLTXohg5cAvQlBMTN9HpCeUIGQfVbr8VjRPLqJCvo IPwLOlvvTqAgrBmvuXLktWb7w6wUXwF6+eoJW4Mkko/TwcIj3qm8EEFj+hdaAYBsF9 wrPlxYPB6PWUs0IgcAzu2iaG9DyFvUMzaDvLU3kwtt3d+qzj2tn8n2X3iyDeJeFifH sqecpZQbOrlzg== Received: by finisterre.sirena.org.uk (Postfix, from userid 1000) id 30DAA1AC58AF; Fri, 10 Apr 2026 11:28:52 +0100 (BST) Date: Fri, 10 Apr 2026 11:28:52 +0100 From: Mark Brown To: Herve Codina Cc: Rob Herring , Liam Girdwood , Krzysztof Kozlowski , Conor Dooley , Saravana Kannan , Jaroslav Kysela , Takashi Iwai , linux-sound@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Christophe Leroy , Thomas Petazzoni Subject: Re: [PATCH 2/4] ASoC: dt-bindings: Add support for the GPIOs driven amplifier Message-ID: References: <20260330101610.57942-1-herve.codina@bootlin.com> <20260330101610.57942-3-herve.codina@bootlin.com> <20260408122901.GA42727-robh@kernel.org> <20260408190932.0ab936b0@bootlin.com> <383635c6-0417-4333-aa9c-9056437d4a5f@sirena.org.uk> <20260410100330.1fc4b97b@bootlin.com> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="o+9W+h3qdmnfJbB1" Content-Disposition: inline In-Reply-To: <20260410100330.1fc4b97b@bootlin.com> X-Cookie: You will be divorced within a year. --o+9W+h3qdmnfJbB1 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Apr 10, 2026 at 10:03:30AM +0200, Herve Codina wrote: > Mark Brown wrote: > > > > I didn't want to set a particular limit related to the number of GP= IOs > > > > used for thje gain value. Of course 2^32 is obviously a lot. =20 > > > > What do you think about 16 for maxItems? =20 > > > What is the most you are aware of? Take that and double it. =20 > > > Seems to me 256 levels would be way more than a human ear could disti= nguish. =20 > > There's plenty of gain controls with way more than 256 bits of > > resolution, though I'm not aware of any that are configured via GPIO. > > The step size and absolute values you want can vary dramatically > > depending on application, possibly in the same system (eg, a DAC that > > can be connected to both headphones or speakers) so you often end up > > making practical adjustments in a small subset of the available range > > but that subset can vary a lot for the same part. > Mark, do you think that max 16 GPIOs could be an acceptable limit? > IMHO, this value is large enough to be used as the limit. That does seem larger than any real system would ever need. --o+9W+h3qdmnfJbB1 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmnY0OMACgkQJNaLcl1U h9Ao1ggAgWdjTX1pvufL7cIl1/RH40GGhnRehBGD8GngAKRTvfoi3/KBcPk29O/u HwFPzD5v1yZIbmq4SZme6Ob/25SUIEIps3YuoLBMH2z21q6CB14p7cs97I7J2XFk PQGkqRkHvzLyG0OjtY6NHG9xzGGViF9qTFvsTWlvYOSjUNZ4wsoYLSOD9XNmjmt6 YRJlvciBynFLtfg1QmO8Gb5Tdxjx398hPugL9griW1z0Oyii2d1MIc7nQ57JLjP9 ld7N7tfqJMVTCpIpGKbYBUx5D+7PXd0J473ig15bAtAkdVMLOTSQDQQIAMY1BCQl 4FfL2rjwoo9GL/o428atk0ph9xOLgg== =eyC5 -----END PGP SIGNATURE----- --o+9W+h3qdmnfJbB1--