Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752463AbdFTUsg (ORCPT ); Tue, 20 Jun 2017 16:48:36 -0400 Received: from mail-qt0-f178.google.com ([209.85.216.178]:33412 "EHLO mail-qt0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751446AbdFTUsd (ORCPT ); Tue, 20 Jun 2017 16:48:33 -0400 Subject: Re: [PATCH v1 1/2] dt-binding: ptp: add bindings document for dte based ptp clock To: Rob Herring , Arun Parameswaran References: <1497299161-6458-1-git-send-email-arun.parameswaran@broadcom.com> <1497299161-6458-2-git-send-email-arun.parameswaran@broadcom.com> <20170618140449.aek7vag22i5lnbhl@rob-hp-laptop> Cc: Richard Cochran , Mark Rutland , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, bcm-kernel-feedback-list@broadcom.com From: Scott Branden Message-ID: <74b85a32-63c5-b7c5-47a2-831504be318e@broadcom.com> Date: Tue, 20 Jun 2017 13:48:18 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <20170618140449.aek7vag22i5lnbhl@rob-hp-laptop> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1893 Lines: 54 Hi Rob, On 17-06-18 07:04 AM, Rob Herring wrote: > On Mon, Jun 12, 2017 at 01:26:00PM -0700, Arun Parameswaran wrote: >> Add device tree binding documentation for the Broadcom DTE >> PTP clock driver. >> >> Signed-off-by: Arun Parameswaran >> --- >> Documentation/devicetree/bindings/ptp/brcm,ptp-dte.txt | 13 +++++++++++++ >> 1 file changed, 13 insertions(+) >> create mode 100644 Documentation/devicetree/bindings/ptp/brcm,ptp-dte.txt >> >> diff --git a/Documentation/devicetree/bindings/ptp/brcm,ptp-dte.txt b/Documentation/devicetree/bindings/ptp/brcm,ptp-dte.txt >> new file mode 100644 >> index 0000000..07590bc >> --- /dev/null >> +++ b/Documentation/devicetree/bindings/ptp/brcm,ptp-dte.txt >> @@ -0,0 +1,13 @@ >> +* Broadcom Digital Timing Engine(DTE) based PTP clock driver > Bindings describe h/w, not drivers. > >> + >> +Required properties: >> +- compatible: should be "brcm,ptp-dte" > Looks too generic. You need SoC specific compatible strings. Rob, could you please help me understand the use of adding SoC specific compatible strings. I still don't get it. It's my understanding that the SoC compatibility string is to future proof against bugs/incompatibilities between different versions of the hardware block due to integration issues or any other reason. You can then compare in your driver because the strings were already used in the dtb. That would make sense if you can't already differentiate what SoC you are running on. But the SoC is already specified in the root of the device tree in the compatible string? Why can't you just use of_machine_is_compatible inside your driver when needed? Please explain what I'm missing. I see other drivers already following the of_machine_is_compatible approach and it makes more sense to me than adding SoC specific compatible strings into every driver. Regards, Scott