From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) (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 0B1D713C9B5; Tue, 26 Mar 2024 15:29:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.176.79.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711466975; cv=none; b=hWPUXez4D6I6KR5ZhH0u8rAW2lwnnaWFhnxSfIa1kwEBMGHzdxG2MJzOjic/hPHHfVoGl0eMv5uqbiz8LoVTS3rsF8zUUgHJK0rgcHVLrdBVQ5tZO10Ba3qE6wdxjyy8K85kRFY9LeaKrwS1+aFwCbilvt/7LW6KdI2cIQ5oBfo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1711466975; c=relaxed/simple; bh=UOqd6ZJ+xqo5YsFIO1ebtjM3W5gPTRG7A1rsHNjT53U=; h=Date:From:To:CC:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=lWcoWviTUdiBBPPzDFESOSlhSQbcx4y4urHRZocf5B15kl5fVYonT2pJPAHenSYU45bslIA+fJESDdeceRNtwDzYsjABIsPYOzuQtYzngOKbl9mEBZdHoL070H/wEt67hJDBFhgzv8qfrtrqu21Hq1ez+mjsXSnjVY72ZY5kVeA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=Huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=185.176.79.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=Huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.18.186.31]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4V3tsB4XDsz6K9K1; Tue, 26 Mar 2024 23:25:02 +0800 (CST) Received: from lhrpeml500005.china.huawei.com (unknown [7.191.163.240]) by mail.maildlp.com (Postfix) with ESMTPS id 71E811406AE; Tue, 26 Mar 2024 23:29:28 +0800 (CST) Received: from localhost (10.202.227.76) by lhrpeml500005.china.huawei.com (7.191.163.240) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.35; Tue, 26 Mar 2024 15:29:27 +0000 Date: Tue, 26 Mar 2024 15:29:27 +0000 From: Jonathan Cameron To: Laurent Pinchart CC: Jonathan Cameron , , , , "Trevor Zaharichuk" , Greg Lytle , "Lars-Peter Clausen" , Rob Herring , "Krzysztof Kozlowski" , Conor Dooley , Sean Nyekjaer , Subject: Re: [PATCH 1/5] dt-bindings: iio: dac: ti,dac5571: Add DAC081C081 support Message-ID: <20240326152927.00006229@Huawei.com> In-Reply-To: <20240325205641.GD23988@pendragon.ideasonboard.com> References: <20240325203245.31660-1-laurent.pinchart@ideasonboard.com> <20240325203245.31660-2-laurent.pinchart@ideasonboard.com> <20240325204857.4f2fd468@jic23-huawei> <20240325205641.GD23988@pendragon.ideasonboard.com> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 4.1.0 (GTK 3.24.33; x86_64-w64-mingw32) Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: lhrpeml500005.china.huawei.com (7.191.163.240) To lhrpeml500005.china.huawei.com (7.191.163.240) On Mon, 25 Mar 2024 22:56:41 +0200 Laurent Pinchart wrote: > Hi Jonathan, >=20 > On Mon, Mar 25, 2024 at 08:48:57PM +0000, Jonathan Cameron wrote: > > On Mon, 25 Mar 2024 22:32:41 +0200 Laurent Pinchart wrote: > > =20 > > > The DAC081C081 is a TI DAC whose software interface is compatible with > > > the DAC5571. It is the 8-bit version of the DAC121C081, already > > > supported by the DAC5571 bindings. Extends the bindings to support th= is > > > chip. > > >=20 > > > Signed-off-by: Laurent Pinchart = =20 > >=20 > > Hi Laurent, > >=20 > > Given it's a part number where no one is going to guess it is compatible > > with the DAC5571 and that we don't have a history of fallback compatibl= es > > I'm fine with this change, but just wanted to ask is a fallback compati= ble > > useful to you to run with older kernels? > >=20 > > I should have noticed when Peter added the dac121c081. If we add a fall= back > > should do that one as well. =20 >=20 > I've indeed noticed that there should have been a fallback for > dac121c081, but didn't stop to ponder why that wasn't the case, and just > went along with the flow :-) I agree a fallback could be useful, which > would then allow dropping patch 2/5 from this series (*). I can do so if > you prefer. >=20 > * This is not entirely true. While the DAC1081C081 is largely compatible > with the DAC5573, they have different values for one of the power-down > resistors (2.5k=CE=A9 instead of 1k=CE=A9 if I recall correctly). To be c= ompletely > accurate, the driver should report that. We could still use the fallback > compatible, reporting the wrong power-down resistor value. >=20 Hmm - Would anyone really care about that value being wrong? I think perhaps that's just about significant enough that maybe a fallback compatible doesn't make sense here. Jonathan > > > --- > > > Documentation/devicetree/bindings/iio/dac/ti,dac5571.yaml | 1 + > > > 1 file changed, 1 insertion(+) > > >=20 > > > diff --git a/Documentation/devicetree/bindings/iio/dac/ti,dac5571.yam= l b/Documentation/devicetree/bindings/iio/dac/ti,dac5571.yaml > > > index 79da0323c327..e59db861e2eb 100644 > > > --- a/Documentation/devicetree/bindings/iio/dac/ti,dac5571.yaml > > > +++ b/Documentation/devicetree/bindings/iio/dac/ti,dac5571.yaml > > > @@ -21,6 +21,7 @@ properties: > > > - ti,dac5573 > > > - ti,dac6573 > > > - ti,dac7573 > > > + - ti,dac081c081 > > > - ti,dac121c081 > > > =20 > > > reg: =20 >=20