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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 30D3CC433DB for ; Mon, 11 Jan 2021 14:33:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EA4EB22473 for ; Mon, 11 Jan 2021 14:33:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388832AbhAKOdR convert rfc822-to-8bit (ORCPT ); Mon, 11 Jan 2021 09:33:17 -0500 Received: from eu-smtp-delivery-151.mimecast.com ([207.82.80.151]:54574 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388790AbhAKOdQ (ORCPT ); Mon, 11 Jan 2021 09:33:16 -0500 Received: from AcuMS.aculab.com (156.67.243.126 [156.67.243.126]) (Using TLS) by relay.mimecast.com with ESMTP id uk-mta-158-SO1OyShiOvaxZ03HwLl3PQ-1; Mon, 11 Jan 2021 14:31:37 +0000 X-MC-Unique: SO1OyShiOvaxZ03HwLl3PQ-1 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) by AcuMS.aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Mon, 11 Jan 2021 14:31:36 +0000 Received: from AcuMS.Aculab.com ([fe80::43c:695e:880f:8750]) by AcuMS.aculab.com ([fe80::43c:695e:880f:8750%12]) with mapi id 15.00.1347.000; Mon, 11 Jan 2021 14:31:36 +0000 From: David Laight To: 'Mikko Perttunen' , "ldewangan@nvidia.com" , "digetx@gmail.com" , "thierry.reding@gmail.com" , "jonathanh@nvidia.com" , "wsa@kernel.org" CC: "linux-i2c@vger.kernel.org" , "linux-tegra@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" Subject: RE: [PATCH] i2c: tegra: Wait for config load atomically while in ISR Thread-Topic: [PATCH] i2c: tegra: Wait for config load atomically while in ISR Thread-Index: AQHW6CIcSfsKH+/ghEGIVUc6PkdaV6oifElA Date: Mon, 11 Jan 2021 14:31:36 +0000 Message-ID: References: <20210111135547.3613092-1-mperttunen@nvidia.com> In-Reply-To: <20210111135547.3613092-1-mperttunen@nvidia.com> Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=C51A453 smtp.mailfrom=david.laight@aculab.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: linux-tegra@vger.kernel.org From: Mikko Perttunen > Sent: 11 January 2021 13:56 > > Upon a communication error, the interrupt handler can call > tegra_i2c_disable_packet_mode. This causes a sleeping poll to happen > unless the current transaction was marked atomic. Since > tegra_i2c_disable_packet_mode is only called from the interrupt path, > make it use atomic waiting always. Spin-waiting in an ISR for anything that it makes sense to do a sleep-wait for at other times is badly broken design. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)