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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 982B2C433F5 for ; Tue, 26 Apr 2022 06:57:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343537AbiDZHAY (ORCPT ); Tue, 26 Apr 2022 03:00:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54534 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239877AbiDZHAV (ORCPT ); Tue, 26 Apr 2022 03:00:21 -0400 Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AB40B4DF7A; Mon, 25 Apr 2022 23:57:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1650956233; x=1682492233; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=jKxbJleSnjKHArCrWhKDUX9hPVC8Trh5097+ZmEWrzI=; b=aNhJMxNyL4j1YLm2K+tA1xzWGdv9Am3xsy6eiY9y5Mrc62YDQT35mSvO 9AB7n/TD+UkO3e7gfYD5qXMVTLL9yFtj7wsfHa9dC+uv67FzuC+o+GyGR aDeiWfiAzW7HoHySutaAKYvpabrj5CKUlefHEkUZnYN9h54+m8bXfbwbK xmfMMlwXsSeAUlcZrjIgNako/lAFrjYuyitTBnsFppfaocyMx0GHBiWVL UEIjENLvJp9F1PKNebLjoNPrsDwWojeaqpVJRswxy/jKN0o48dDz1qAno hxxnjfM4aww5xGKSvvI/JafbVAPYYmoa7POFs6lKck9E8xqzqs/vcQ21L g==; X-IronPort-AV: E=McAfee;i="6400,9594,10328"; a="264998480" X-IronPort-AV: E=Sophos;i="5.90,290,1643702400"; d="scan'208";a="264998480" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Apr 2022 23:57:13 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.90,290,1643702400"; d="scan'208";a="704917710" Received: from kuha.fi.intel.com ([10.237.72.185]) by fmsmga001.fm.intel.com with SMTP; 25 Apr 2022 23:57:08 -0700 Received: by kuha.fi.intel.com (sSMTP sendmail emulation); Tue, 26 Apr 2022 09:57:07 +0300 Date: Tue, 26 Apr 2022 09:57:07 +0300 From: Heikki Krogerus To: Roger Quadros Cc: Aswath Govindraju , Vignesh Raghavendra , Kishon Vijay Abraham I , Greg Kroah-Hartman , Rob Herring , Krzysztof Kozlowski , Sven Peter , Alyssa Rosenzweig , Hector Martin , Martin Kepplinger , Bryan O'Donoghue , linux-usb@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] dt-bindings: usb: tps6598x: Make the interrupts property optional Message-ID: References: <20220414083120.22535-1-a-govindraju@ti.com> <20220414083120.22535-2-a-govindraju@ti.com> <56c72151-af5f-366b-b17f-24b9fb6264da@ti.com> <89f7d69a-4fc8-33cc-d9ca-5c50dc5381ab@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <89f7d69a-4fc8-33cc-d9ca-5c50dc5381ab@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 26, 2022 at 09:42:31AM +0300, Roger Quadros wrote: > Hi, > > On 22/04/2022 08:07, Aswath Govindraju wrote: > > Hi Roger, > > > > On 21/04/22 00:46, Roger Quadros wrote: > >> Hi, > >> > >> On 18/04/2022 08:19, Aswath Govindraju wrote: > >>> Hi Roger, > >>> > >>> On 14/04/22 23:40, Roger Quadros wrote: > >>>> Hi, > >>>> > >>>> On 14/04/2022 11:31, Aswath Govindraju wrote: > >>>>> Support for polling has been added in the driver, which will be used by > >>>>> default if interrupts property is not populated. Therefore, remove > >>>>> interrupts and interrupt-names from the required properties and add a note > >>>>> under interrupts property describing the above support in driver. > >>>>> > >>>>> Suggested-by: Roger Quadros > >>>> > >>>> I did not suggest to make interrupts optional by default. > >>>> > >>>> What I suggested was that if a DT property exists to explicitly > >>>> indicate polling mode then interrupts are not required. > >>>> > >>> > >>> ohh okay, got it. However, may I know if adding a dt property to > >>> indicate polling for aiding the driver, is the correct approach to model it? > >>> > >>> In terms of modelling hardware, as interrupts are not connected we are > >>> not populating the interrupts property. Shouldn't that be all. If we are > >>> adding a property explicitly to indicate polling that can be used by > >>> driver, wouldn't that be a software aid being added in the device tree? > >> > >> The hardware (tps6598x chip) has an interrupt pin and is expected to be used > >> in normal case. > >> > >> Some buggy boards might have forgot to connect it. We are adding polling mode only for these buggy boards. ;) > >> So polling mode is an exception. > >> > > > > Yes as you mentioned the interrupt line is expected to connected but > > there could be cases where there are not enough pins on the SoC and > > polling is used intentionally. In these cases this would be a feature > > rather than a bug. > > I do not agree that this is a feature but a board defect. You can always use > a GPIO expander to add more GPIOs than the SoC can provide. > > Type-C events are asynchronous and polling is a waste of CPU time. > What will you do if system suspends and you need to wake up on Type-C > status change? > So polling mode is just an exception for the defective boards or could > be used for debugging. > > > > > Also, I feel like not adding interrupts property in the dt nodes will > > indicate polling. My question is why are we adding an extra property > > (which is being used only as an aid in the driver) when this feature can > > be modeled by making interrupts property optional. > > Because interrupt property was not originally optional for this driver. > > I would like to hear what Heikki has to say about this. > > Any thoughts Heikki? I think the question is generic. How should DT describe the connection/lack of connection? Rob should comment on this. thanks, > cheers, > -roger > > > > > Thanks, > > Aswath > > > >> cheers, > >> -roger > >> > >>> > >>> Thanks, > >>> Aswath > >>> > >>>>> Signed-off-by: Aswath Govindraju > >>>>> --- > >>>>> Documentation/devicetree/bindings/usb/ti,tps6598x.yaml | 4 ++-- > >>>>> 1 file changed, 2 insertions(+), 2 deletions(-) > >>>>> > >>>>> diff --git a/Documentation/devicetree/bindings/usb/ti,tps6598x.yaml b/Documentation/devicetree/bindings/usb/ti,tps6598x.yaml > >>>>> index a4c53b1f1af3..1c4b8c6233e5 100644 > >>>>> --- a/Documentation/devicetree/bindings/usb/ti,tps6598x.yaml > >>>>> +++ b/Documentation/devicetree/bindings/usb/ti,tps6598x.yaml > >>>>> @@ -25,6 +25,8 @@ properties: > >>>>> > >>>>> interrupts: > >>>>> maxItems: 1 > >>>>> + description: > >>>>> + If interrupts are not populated then by default polling will be used. > >>>>> > >>>>> interrupt-names: > >>>>> items: > >>>>> @@ -33,8 +35,6 @@ properties: > >>>>> required: > >>>>> - compatible > >>>>> - reg > >>>>> - - interrupts > >>>>> - - interrupt-names > >>>>> > >>>>> additionalProperties: true > >>>>> > >>>> > >>>> cheers, > >>>> -roger > > > > -- heikki