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 68CD9C433FE for ; Thu, 12 May 2022 16:49:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1356515AbiELQtJ (ORCPT ); Thu, 12 May 2022 12:49:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42628 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348145AbiELQtI (ORCPT ); Thu, 12 May 2022 12:49:08 -0400 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 90ECD268649; Thu, 12 May 2022 09:49:06 -0700 (PDT) Received: from fraeml704-chm.china.huawei.com (unknown [172.18.147.226]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4Kzd2T6nn5z684JT; Fri, 13 May 2022 00:46:09 +0800 (CST) Received: from lhreml710-chm.china.huawei.com (10.201.108.61) by fraeml704-chm.china.huawei.com (10.206.15.53) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2375.24; Thu, 12 May 2022 18:49:03 +0200 Received: from localhost (10.81.210.133) by lhreml710-chm.china.huawei.com (10.201.108.61) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Thu, 12 May 2022 17:49:03 +0100 Date: Thu, 12 May 2022 17:48:59 +0100 From: Jonathan Cameron To: Eddie James CC: , , , , , , , Subject: Re: [PATCH v2 0/2] iio: humidity: si7020: Check device property for skipping reset in probe Message-ID: <20220512174859.000042b6@Huawei.com> In-Reply-To: <20220512162020.33450-1-eajames@linux.ibm.com> References: <20220512162020.33450-1-eajames@linux.ibm.com> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 4.0.0 (GTK+ 3.24.29; i686-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.81.210.133] X-ClientProxiedBy: lhreml720-chm.china.huawei.com (10.201.108.71) To lhreml710-chm.china.huawei.com (10.201.108.61) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Thu, 12 May 2022 11:20:18 -0500 Eddie James wrote: > I2C commands issued after the SI7020 is starting up or after reset > can potentially upset the startup sequence. Therefore, the host > needs to wait for the startup sequence to finish before issuing > further i2c commands. This is impractical in cases where the SI7020 > is on a shared bus or behind a mux, which may switch channels at > any time (generating I2C traffic). Therefore, check for a device > property that indicates that the driver should skip resetting the > device when probing. Why not lock the bus? It's not ideal, but then not resetting and hence potentially ending up in an unknown state isn't great either. Jonathan > > Changes since v1: > - Fix dt binding document > > Eddie James (2): > dt-bindings: iio: humidity: Add si7020 bindings > iio: humidity: si7020: Check device property for skipping reset in probe > > .../bindings/iio/humidity/silabs,si7020.yaml | 47 +++++++++++++++++++ > .../devicetree/bindings/trivial-devices.yaml | 2 - > drivers/iio/humidity/si7020.c | 14 +++--- > 3 files changed, 55 insertions(+), 8 deletions(-) > create mode 100644 Documentation/devicetree/bindings/iio/humidity/silabs,si7020.yaml >