From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtpout-04.galae.net (smtpout-04.galae.net [185.171.202.116]) (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 1E6F0274B23; Fri, 10 Apr 2026 08:03:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.171.202.116 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775808235; cv=none; b=c5R4N+i9cYOXeX/D7EB3zgR7d2YhNbfFFIJ6U76Rz/2t5rPwheV19nahl/pkJD992uF9IvrUBRNTcNBmyS2A4FL3v70fe9uudMZoSMXQs/a4He9dQBI4Y/JcIB2O2ch8g/c9znYePJxo4RVeGTwtBBeB/q//qFNlfUi9Y2Cmbgg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775808235; c=relaxed/simple; bh=GqVja/wYMr+GIx1XTa/Um3CGRHwOCAW2GPX9x16qv54=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=EKqLnsuCpIQOMrxQcckepGgOrHpKt9fJoE3Ln2kbCiluhjcwD9fSQhGecSHB4aAVJLpyQ2/CHJKKyK+d9mpg+1XskjzGMgf+OjmJCAruVADRFsm9+0Y2BV0nmcejVPKVQW4+HWKALu8cCh6HCeQ89AOV59+jxxs3NWxeRteMrQc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com; spf=pass smtp.mailfrom=bootlin.com; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b=w211sklA; arc=none smtp.client-ip=185.171.202.116 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=bootlin.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b="w211sklA" Received: from smtpout-01.galae.net (unknown [212.83.139.233]) by smtpout-04.galae.net (Postfix) with ESMTPS id C5D47C5C1A4; Fri, 10 Apr 2026 08:04:20 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id 9392B6042F; Fri, 10 Apr 2026 08:03:35 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 26727104501FC; Fri, 10 Apr 2026 10:03:31 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1775808214; h=from:subject:date:message-id:to:cc:mime-version:content-type: content-transfer-encoding:in-reply-to:references; bh=+FK7vpYb+MDnT94F6A494bLVe1AhIg54zS2mn/Kup+E=; b=w211sklA1zi8mjJf+Nq2ofIkIM33NpCLnA2TeOjxlwtYuE4NUFT+FDK+bLsvWiiuDPmsN1 glZSJDu7TwEpI3KnPRuB7fuLIhB8z6W5TtBleutuN0i3Gs56IcrQ0u2aKgB27261K5ifmo UV6zXhaloQ0mKeB5q5AE7Zc/o3ScrJGQJeZ505ZmlRjuaez35WrWrh8wrCm/d8T/HA3hUA M4c4IUGF/LCgICOkwuz87mkRjKp4tXa6SG7Fvak0Qk8BOmoQLbyr633s87mzqScNMLAj8L q2TMX48icEqjKWR/wiUk8FnAvqWyHg9kMdtbZbyAvpUJ9Msj3khwtME9tMcztg== Date: Fri, 10 Apr 2026 10:03:30 +0200 From: Herve Codina To: Mark Brown 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: <20260410100330.1fc4b97b@bootlin.com> In-Reply-To: <383635c6-0417-4333-aa9c-9056437d4a5f@sirena.org.uk> 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> Organization: Bootlin X-Mailer: Claws Mail 4.3.1 (GTK 3.24.49; x86_64-redhat-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8bit X-Last-TLS-Session-Version: TLSv1.3 Hi Mark, Rob, On Thu, 9 Apr 2026 16:26:25 +0100 Mark Brown wrote: > > > I didn't want to set a particular limit related to the number of GPIOs > > > used for thje gain value. Of course 2^32 is obviously a lot. > > > > What do you think about 16 for maxItems? > > > What is the most you are aware of? Take that and double it. > > > Seems to me 256 levels would be way more than a human ear could distinguish. > > 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. > > > I guess my point was that really we could deprecate simple-amplifier > > binding because this one can handle it and more. But I'm not > > suggesting we do that yet. > > That's my thinking. Fine for me to, at the end, deprecate the simple-amplifier.