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 BB4766F06A; Sun, 5 May 2024 19:46:18 +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=1714938378; cv=none; b=qycwqr+u2IZYFJX2R0c6D+2wd7dICvVlqarPg/CtDW6tzof0rPUlmjbSvvBfaEtnQrutiTygff8R1sFXXOy3kekBzous67Mtl93IWLcumd/UGGo6r4vF30jWF9YMuCBVKivZvhVTPJ/R7k1t2EYlIiMQOjDsanJwECbQG3mQn+k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714938378; c=relaxed/simple; bh=0xWVR+hZm1hbLhnVuDoCeCqqADDcUffOxV9wWM5nJTQ=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=FPC7gUBe4DuoBZwMtD4eBrpAIUrlUP8y+stme7myudLiJ1xTmS0B8ZBCsr9TNpmPVOV9uCDdcWi0SvtjzkUD2bCRxh8hC741Efa3r5kGIZ23nG32xi9nTdb2H7oLXqxBa+W98qmvLAW+wa85+U24bpqxmufLBeIx/bLDVb7sCNw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=E4iEXlVw; 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="E4iEXlVw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 27D52C116B1; Sun, 5 May 2024 19:46:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1714938378; bh=0xWVR+hZm1hbLhnVuDoCeCqqADDcUffOxV9wWM5nJTQ=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=E4iEXlVwv03Q1LXj60ldMa3YKet2nlH76YkVFc6V/+H3oTyRcrtr/hnRfT4zgZtUn PKfGNdrVT/CDB9d63NfQAMPH/ZARA8WyU5wSqWm9r1S1TyBPpBg1njo4jNvwEUf71A MUKNRGjwhWP4hxiM/x8/vRKT+FMhCH+61w1ktYgp6yZFAlKuABTmEeV52YNJC7Idn9 Xdcp4dPyJchJ9EolLB5C0HK/RK9gsAS62/txGmeFN/dvX+4UWUFFX9gQ/fWRPOO1Kq yJxkRtbsWW5MN3cRYbzb1uFpYELxY+59/qO91D5lDlskT2dWReVNfK8ch7zd5gINQU SFdQT2E8h8fcg== Date: Sun, 5 May 2024 20:46:02 +0100 From: Jonathan Cameron To: Conor Dooley Cc: Alisa-Dariana Roman , michael.hennerich@analog.com, linux-iio@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, alexandru.tachici@analog.com, lars@metafoo.de, robh@kernel.org, krzysztof.kozlowski+dt@linaro.org, conor+dt@kernel.org, lgirdwood@gmail.com, broonie@kernel.org, andy@kernel.org, nuno.sa@analog.com, marcelo.schmitt@analog.com, bigunclemax@gmail.com, dlechner@baylibre.com, okan.sahin@analog.com, fr0st61te@gmail.com, alisa.roman@analog.com, marcus.folkesson@gmail.com, schnelle@linux.ibm.com, liambeguin@gmail.com Subject: Re: [PATCH v7 5/6] dt-bindings: iio: adc: ad7192: Add AD7194 support Message-ID: <20240505204602.5d4cbfa0@jic23-huawei> In-Reply-To: <20240430-winnings-wrongness-32328ccfe3b5@spud> References: <20240430162946.589423-1-alisa.roman@analog.com> <20240430162946.589423-6-alisa.roman@analog.com> <20240430-winnings-wrongness-32328ccfe3b5@spud> X-Mailer: Claws Mail 4.2.0 (GTK 3.24.41; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Tue, 30 Apr 2024 18:21:01 +0100 Conor Dooley wrote: > On Tue, Apr 30, 2024 at 07:29:45PM +0300, Alisa-Dariana Roman wrote: > > + diff-channels: > > + description: > > + Both inputs can be connected to pins AIN1 to AIN16 by choosing the > > + appropriate value from 1 to 16. > > + items: > > + minimum: 1 > > + maximum: 16 > > + > > + single-channel: > > + description: > > + Positive input can be connected to pins AIN1 to AIN16 by choosing the > > + appropriate value from 1 to 16. Negative input is connected to AINCOM. > > + items: > > + minimum: 1 > > + maximum: 16 > > Up to 16 differential channels and 16 single-ended channels, but only 16 > pins? Would the number of differential channels not max out at 8? May not really be limited to 16 differential. Many chips use general purpose muxes on both sides so you can do all combinations. In practice that's normally pointless. A more useful case is to do all but one channel as positive inputs and the remaining channel as the negative for those 15 differential channels. This is effectively the same as doing pseudo differential channels, but on more flexible hardware. This is in contrast to a device that only supports pseudo differential where there is a special pin for the negative (this device has that as well as full muxes on the other 16 lines). Having said all that. The ad7194 datasheet says 8 differential channels.. I have no idea why though... Maybe something to do with the mux switching? Or maybe assumption is that if you want to do pseudo differential you'll use the pseudo differential mode rather than wasting hardware? Jonathan