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 0BC5DC433F5 for ; Mon, 2 May 2022 05:31:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1383336AbiEBFe6 (ORCPT ); Mon, 2 May 2022 01:34:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50130 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236108AbiEBFew (ORCPT ); Mon, 2 May 2022 01:34:52 -0400 Received: from lelv0142.ext.ti.com (lelv0142.ext.ti.com [198.47.23.249]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1E87F1BEBC; Sun, 1 May 2022 22:31:23 -0700 (PDT) Received: from fllv0035.itg.ti.com ([10.64.41.0]) by lelv0142.ext.ti.com (8.15.2/8.15.2) with ESMTP id 2425UpP3091238; Mon, 2 May 2022 00:30:51 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1651469451; bh=BUXxiuFFD86bcXlTaA9jXgKOVSHgEET95R0XpQs0bMQ=; h=Date:Subject:To:CC:References:From:In-Reply-To; b=l3Jlr9Z5xiaWfnZKQS6pfGDWppRzOuu750uIjqgtewkBtXalcoGjkX1/tIK3Q4Mki +t4JRYNurXz8MEcaPRvQ6d+NMBLawRFzG/8KucDFd5pec7ndEVlfhfk+tLkR9LT6FR 8ZawmYDt5bKQPO73r4XMmLzF/Dp2vd1Pa2eG9Ems= Received: from DLEE105.ent.ti.com (dlee105.ent.ti.com [157.170.170.35]) by fllv0035.itg.ti.com (8.15.2/8.15.2) with ESMTPS id 2425Upaj064608 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Mon, 2 May 2022 00:30:51 -0500 Received: from DLEE104.ent.ti.com (157.170.170.34) by DLEE105.ent.ti.com (157.170.170.35) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2308.14; Mon, 2 May 2022 00:30:50 -0500 Received: from lelv0326.itg.ti.com (10.180.67.84) by DLEE104.ent.ti.com (157.170.170.34) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2308.14 via Frontend Transport; Mon, 2 May 2022 00:30:49 -0500 Received: from [172.24.145.198] (ileax41-snat.itg.ti.com [10.172.224.153]) by lelv0326.itg.ti.com (8.15.2/8.15.2) with ESMTP id 2425UjCk005241; Mon, 2 May 2022 00:30:45 -0500 Message-ID: Date: Mon, 2 May 2022 11:00:44 +0530 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Subject: Re: [PATCH 1/2] dt-bindings: usb: tps6598x: Make the interrupts property optional Content-Language: en-US To: Heikki Krogerus , Roger Quadros , Rob Herring CC: Vignesh Raghavendra , Kishon Vijay Abraham I , Greg Kroah-Hartman , Krzysztof Kozlowski , Sven Peter , Alyssa Rosenzweig , Hector Martin , Martin Kepplinger , "Bryan O'Donoghue" , , , 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> From: Aswath Govindraju In-Reply-To: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Rob, On 26/04/22 12:27, Heikki Krogerus wrote: > 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. > A gentle ping regarding this. Thanks, Aswath > 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 >>> >>> >