From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8487EC0044C for ; Sat, 3 Nov 2018 10:36:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 24FEE20833 for ; Sat, 3 Nov 2018 10:36:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="TCJUD5La" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 24FEE20833 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728129AbeKCTrR (ORCPT ); Sat, 3 Nov 2018 15:47:17 -0400 Received: from mail.kernel.org ([198.145.29.99]:52948 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726711AbeKCTrQ (ORCPT ); Sat, 3 Nov 2018 15:47:16 -0400 Received: from archlinux (cpc91196-cmbg18-2-0-cust659.5-4.cable.virginm.net [81.96.234.148]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D830B2081F; Sat, 3 Nov 2018 10:36:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1541241383; bh=ZhoVBX/bIWNfL4OER2O1im/MwIONPmifXGKrRTRrOiI=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=TCJUD5LaOAD1/VdeVBbnYBmsLRmxip1vY48/fxURG03HRGzIUEMFzA3qwfU4B9isy hZNMEezywrBBWFRsNB3rgZv4KUOgpaqw4gvWbfozQyEjOZWqAQFWSrlcCR4LIDNqkO RyRHR9u/oqmDcpskzdNpJFi1bi2Q/JmCAozvVFag= Date: Sat, 3 Nov 2018 10:36:19 +0000 From: Jonathan Cameron To: Carlos Iglesias Cc: "linux-kernel@vger.kernel.org" , "robh+dt@kernel.org" , "mark.rutland@arm.com" , "knaack.h@gmx.de" , "lars@metafoo.de" , "pmeerw@pmeerw.net" , "linux-iio@vger.kernel.org" , "devicetree@vger.kernel.org" , Dan O'Donovan Subject: Re: [PATCH 1/2] dt-bindings: iio: pressure: Add support for Honeywell HSC SPI sensors Message-ID: <20181103103619.7c4addd3@archlinux> In-Reply-To: <0dbb2254-8035-b498-6302-26bc3a2219ca@emutex.com> References: <20181026181406.14545-1-carlos.iglesias@emutex.com> <20181026181406.14545-2-carlos.iglesias@emutex.com> <20181028173842.580ba1d4@archlinux> <0dbb2254-8035-b498-6302-26bc3a2219ca@emutex.com> X-Mailer: Claws Mail 3.17.1 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Rob, just to draw your attention, some discussion around spi-max-frequency that you might want to look at below. On Tue, 30 Oct 2018 15:56:58 +0000 Carlos Iglesias wrote: > Please see comments inline below. Hi Carlos, Please try to use an email client (or configure yours to do it) that adds indentation to each level of reply. It's somewhat fiddly to separate the different parts of the conversation! > > On 10/28/18 5:38 PM, Jonathan Cameron wrote: > > On Fri, 26 Oct 2018 18:14:36 +0000 > Carlos Iglesias wrote: > > > > Add device tree bindings for the HSC pressure sensors. > > Signed-off-by: Carlos Iglesias > --- > .../bindings/iio/pressure/hsc_spi.txt | 85 +++++++++++++++++++ > 1 file changed, 85 insertions(+) > create mode 100644 Documentation/devicetree/bindings/iio/pressure/hsc_spi.txt > > diff --git a/Documentation/devicetree/bindings/iio/pressure/hsc_spi.txt b/Documentation/devicetree/bindings/iio/pressure/hsc_spi.txt > new file mode 100644 > index 000000000000..2302d6eef7c7 > --- /dev/null > +++ b/Documentation/devicetree/bindings/iio/pressure/hsc_spi.txt > @@ -0,0 +1,85 @@ > +Honeywell HSC Series of Pressure Sensors > + > +Pressure sensors from Honeywell with analog, I2C and SPI interfaces > + > +Required properties: > +- compatible: selects the sensor model; must be one of the following > + "honeywell,hsc001baa" > + "honeywell,hsc001bab" > + "honeywell,hsc001bac" > + "honeywell,hsc001baf" > + "honeywell,hsc1_6baa" > + "honeywell,hsc1_6bab" > + "honeywell,hsc1_6bac" > + "honeywell,hsc1_6baf" > + "honeywell,hsc2_5baa" > + "honeywell,hsc2_5bab" > + "honeywell,hsc2_5bac" > + "honeywell,hsc2_5baf" > + "honeywell,hsc004baa" > + "honeywell,hsc004bab" > + "honeywell,hsc004bac" > + "honeywell,hsc004baf" > + "honeywell,hsc006baa" > + "honeywell,hsc006bab" > + "honeywell,hsc006bac" > + "honeywell,hsc006baf" > + "honeywell,hsc010baa" > + "honeywell,hsc010bab" > + "honeywell,hsc010bac" > + "honeywell,hsc010baf" > + "honeywell,hsc100kaa" > + "honeywell,hsc100kab" > + "honeywell,hsc100kac" > + "honeywell,hsc100kaf" > + "honeywell,hsc160kaa" > + "honeywell,hsc160kab" > + "honeywell,hsc160kac" > + "honeywell,hsc160kaf" > + "honeywell,hsc250kaa" > + "honeywell,hsc250kab" > + "honeywell,hsc250kac" > + "honeywell,hsc250kaf" > + "honeywell,hsc400kaa" > + "honeywell,hsc400kab" > + "honeywell,hsc400kac" > + "honeywell,hsc400kaf" > + "honeywell,hsc600kaa" > + "honeywell,hsc600kab" > + "honeywell,hsc600kac" > + "honeywell,hsc600kaf" > + "honeywell,hsc001gaa" > + "honeywell,hsc001gab" > + "honeywell,hsc001gac" > + "honeywell,hsc001gaf" > + "honeywell,hsc015paa" > + "honeywell,hsc015pab" > + "honeywell,hsc015pac" > + "honeywell,hsc015paf" > + "honeywell,hsc030paa" > + "honeywell,hsc030pab" > + "honeywell,hsc030pac" > + "honeywell,hsc030paf" > + "honeywell,hsc060paa" > + "honeywell,hsc060pab" > + "honeywell,hsc060pac" > + "honeywell,hsc060paf" > + "honeywell,hsc100paa" > + "honeywell,hsc100pab" > + "honeywell,hsc100pac" > + "honeywell,hsc100paf" > + "honeywell,hsc150paa" > + "honeywell,hsc150pab" > + "honeywell,hsc150pac" > + "honeywell,hsc150paf" > +- reg: the SPI chip select number used by the sensor. > +- spi-max-frequency: maximum clock frequency (Hz) used for the SPI bus. > + The maximum value supported by the sensors is 400000. > > > As Rob pointed out in a few reviews this week, the devicetree binding > for this should only be applying a tighter bound than either the > device or the bus master. So something introduced by the board > layout for example, or a level convertor.. > > Jonathan > > Checking the devicetree bindings files of other spi sensors I see a frequent approach is to include a reference to Documentation/devicetree/bindings/spi/spi-bus.txt, for example: > > Property rules described in Documentation/devicetree/bindings/spi/spi-bus.txt apply. In particular, "reg" and "spi-max-frequency" properties must be given. The point is that spi-max-frequency doesn't actually need to be given. If the fine with which ever is lower of that supported by the device and that supported by the master then it will use that without spi-max-frequency being provided. I agree this wasn't previously my understanding but it does make sense. No obvious reason why this value would need providing by DT unless there is a board issue that neither of the 'ends' can see. We might want to look at cleaning this up in general through the bindings (and making sure device drivers apply there own maximums). Rob is this a worthwhile cleanup? > > Maybe it would be a better option to place such a note instead of the "reg" and "spi-max-frequency" points. What do you think? > > Sorry, I was not aware of Rob Herring's previous comments on this topic, I am not subscribed to the LKML. Sure, I wasn't aware of them until that day anyway ;) Thanks, Jonathan > > > > > + > +Example: > + > + hsc_spi0: hsc@0 { > + compatible = "honeywell,hsc010baa"; > + reg = <0>; > + spi-max-frequency = <400000>; > + }; > > > >