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 5E8B7C433FE for ; Sat, 14 May 2022 13:32:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230246AbiENNcE (ORCPT ); Sat, 14 May 2022 09:32:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44190 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232476AbiENNcB (ORCPT ); Sat, 14 May 2022 09:32:01 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5DF10167ED; Sat, 14 May 2022 06:31:59 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 136D9B80759; Sat, 14 May 2022 13:31:57 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2A530C340EE; Sat, 14 May 2022 13:31:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1652535115; bh=TExNkCJIyi7sDz+kd0um9+TpmBxdCc8saAXZNsfA+Jo=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=NTYaemDyM2EcpaBTJbdwga+I34SCsAkZ43SzvYi2A/h9HXiFUqi6fQWUc+afC8sKD aDeorUuiE2Wy4pfaEM9+KVfnH/dIglvw+dHdI0mexse6ssIC/jUkC1stFGoWvjhhrl fh8CwBLQTA2FTj59soeJcdLvtfcoWNSxBMbtrUlVNW+1M7Rjt0vIzrmADN7pkizh9+ GvGssv6P5m/QIGjO9itQlWhUQ5pBos1CZsxtZWQq6BgjJ2I049t5YAS2ExJn5mUB0C 5HBvTQZVHQQ3L0xLIh2HCtH9kE0UGz1/HwoiHCJszvi5tmsFRwsvaxjzMBUR/BEAO0 OC0wsubNWhVWA== Date: Sat, 14 May 2022 14:40:30 +0100 From: Jonathan Cameron To: Eddie James Cc: Jonathan Cameron , linux-iio@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, krzysztof.kozlowski+dt@linaro.org, robh+dt@kernel.org, lars@metafoo.de, miltonm@us.ibm.com Subject: Re: [PATCH v2 0/2] iio: humidity: si7020: Check device property for skipping reset in probe Message-ID: <20220514144030.7a57da70@jic23-huawei> In-Reply-To: References: <20220512162020.33450-1-eajames@linux.ibm.com> <20220512174859.000042b6@Huawei.com> X-Mailer: Claws Mail 4.1.0 (GTK 3.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Thu, 12 May 2022 14:11:06 -0500 Eddie James wrote: > On 5/12/22 11:48, Jonathan Cameron wrote: > > 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. > > > Also, I should mention that in our case we can rely on the power on > reset, so the device should be in a known state. Until someone unbinds and rebinds the driver... It's very hard to have any guarantees once users are involved :) Jonathan > > Eddie > > > > > > 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 > >>