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 6FE7A227BAB; Thu, 5 Dec 2024 18:15:03 +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=1733422503; cv=none; b=bq8vl78637oqpxqT2x/l6UqKf5QCeYO16y+ldp+PksqDIRdwSE7QkK6x68iaaBN8j5/YNnvWQrkuqxofcy4RW5mAs9RYoIPMB1PlSTkGoUrkmz9tWkDwOObbcb7ulNfBwKPE6v3YBFs+oxpyqXfzyGxqe9FwW+aP6bwA2PYGwRk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733422503; c=relaxed/simple; bh=xxzkZHV8bU8zs+Js+tnRGqLeNA9OX9QiQEWbAm9heVA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=VyQQQWxdPzQLH0sm4FAZhyi+pCk7Ztv8BnljrRuwqSA4mPZQeogm1gmf5zdzPg3fU4+xUESyrEALBUxiUD/6ixXNvZaNZGegthSUUJaB+LuDl6xMktTvLW8A78Z6FbrcT3vzYpmvwEL0ZZHhht4Ngfn/t01dX6UC5oND1shhE/g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Mo0B6B0p; 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="Mo0B6B0p" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A206AC4CEDC; Thu, 5 Dec 2024 18:15:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1733422503; bh=xxzkZHV8bU8zs+Js+tnRGqLeNA9OX9QiQEWbAm9heVA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Mo0B6B0p5goBaxZc60eCkjV/pG80zcP21okgeAi69WhLmLwsFwi1ZdS6bZjWPCRos w85hukDb78kVY9f9J74R1a+EgKnBSwLWpeowwIZUjpu1ljyRuRYsUck3jK5CTkU28d RdPFsUT3b+a20lEPkfejy+PUj1jfwnI6hhVkukOygjM3GSz7dd2RDoUS3TcDuC3oip WgQXiwBKWonpHIK+UJyXTomxDm4tAvN1PkbQpBPBIWSRakxCXjtx4LWWjeh7rLE/hP Q7C99+SP3shP19HizyEZkBniAAfeRzhfz3x83zm08FJl6NdxFHa5DuHNVjjIW7e+X8 liKe/5wSFyUaQ== Date: Thu, 5 Dec 2024 18:14:59 +0000 From: Conor Dooley To: "Miclaus, Antoniu" Cc: Jonathan Cameron , "robh@kernel.org" , "conor+dt@kernel.org" , "linux-iio@vger.kernel.org" , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-pwm@vger.kernel.org" Subject: Re: [PATCH v3 1/2] dt-bindings: iio: adf4371: add rdiv2 and doubler Message-ID: <20241205-tummy-snorkel-2765ce63dc3f@spud> References: <20241129153356.63547-1-antoniu.miclaus@analog.com> <20241129153356.63547-2-antoniu.miclaus@analog.com> <20241130163948.269289dc@jic23-huawei> 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-sha256; protocol="application/pgp-signature"; boundary="zhbonRGPyfEtWeAZ" Content-Disposition: inline In-Reply-To: --zhbonRGPyfEtWeAZ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Dec 02, 2024 at 09:47:21AM +0000, Miclaus, Antoniu wrote: > > -----Original Message----- > > From: Jonathan Cameron > > Sent: Saturday, November 30, 2024 6:40 PM > > To: Miclaus, Antoniu > > Cc: robh@kernel.org; conor+dt@kernel.org; linux-iio@vger.kernel.org; > > devicetree@vger.kernel.org; linux-kernel@vger.kernel.org; linux- > > pwm@vger.kernel.org > > Subject: Re: [PATCH v3 1/2] dt-bindings: iio: adf4371: add rdiv2 and do= ubler > >=20 > > [External] > >=20 > > On Fri, 29 Nov 2024 17:33:52 +0200 > > Antoniu Miclaus wrote: > >=20 > > > Add support for reference doubler enable and reference divide by 2 > > > clock. > > > > > > Both of these blocks are optional on the frequency path within the > > > chip and can be adjusted depending on the custom needs of the > > > applications. > > Thanks for the additional info! > > > > > > The doubler is useful for increasing the PFD comparison frequency > > > which will result in a noise performance of the system. > >=20 > > So I'll play devil's advocate. Improved noise performance sounds > > good. If it doesn't take me out of range of allowed frequencies, why > > would I not turn it on? What is it about the surrounding circuitry > > etc that would make this a bad idea for some uses of this chip > > but not others? Did I miss a response to this? > > > The reference divide by 2 divides the reference signal by 2, > > > resulting in a 50% duty cycle PFD frequency. > >=20 > > why would I want one of those? My 'guess' is this makes sense > > if the reference frequency is too high after the application of > > the scaling done by the 5 bit counter. In effect it means the > > division circuitry does divide by 1-31, 2-64 in steps of 2. > >=20 > > That could all be wrapped up in the existing control of the > > frequency, and so far I'm still not seeing a strong reason why > > it belongs in DT. > >=20 > > The 50% cycle thing is a bit of a red herring as assuming it > > is triggered on say the rising edge of the high frequency signal > > to toggle the divided signal, that will always be a 50% duty cycle. > >=20 > As mentioned in the cover letter this was mostly a request from > customers that are using adf4371 on a large scale and they need > these features to be controllable somehow by the user. >=20 > Since these attributes were already validated as devicetree properties > for adf4350 on mainline, I found this as the best approach to satisfy > both ends. Probably shouldn't have allowed it then, but things were different a decade ago. --zhbonRGPyfEtWeAZ Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQRh246EGq/8RLhDjO14tDGHoIJi0gUCZ1HtowAKCRB4tDGHoIJi 0shwAP4iirJ0ArRmeKHavHbxz14PFZAFnod9h9613bjP1F8svQD/cWqXXRG/KZnF DML/oiTyMIdibfcqyg9ac+JD/etqfgQ= =rYRh -----END PGP SIGNATURE----- --zhbonRGPyfEtWeAZ--