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 9F295C433FE for ; Fri, 13 May 2022 17:59:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241034AbiEMR7e (ORCPT ); Fri, 13 May 2022 13:59:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49826 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234536AbiEMR7e (ORCPT ); Fri, 13 May 2022 13:59:34 -0400 Received: from mail-lf1-x130.google.com (mail-lf1-x130.google.com [IPv6:2a00:1450:4864:20::130]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7B3152610A; Fri, 13 May 2022 10:59:32 -0700 (PDT) Received: by mail-lf1-x130.google.com with SMTP id y32so15801241lfa.6; Fri, 13 May 2022 10:59:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=message-id:date:mime-version:user-agent:subject:content-language:to :cc:references:from:in-reply-to:content-transfer-encoding; bh=F9nVmxbxhPUjXlAFgxWdPottc/POpyAnJKeZJvdJb3Q=; b=nDJ5l8PJQN6ErdgB5BQL9UoNqthpJEj8Ph+b6M5H6gCD5YJQOQLn9uVZW0TCxjV5d3 xWk/gd9SFSNISUuInNDzkEePTpVfVBA82xTxYgz5IIksYKh91DVz57K7Ikjnqx0K5gC5 5sKzwXwNFBue6IdUNQxncSJksQy+MYHAg25vbmbX80bMyfKEjLGNPP7es0kWv/bEIXKR Hw2wsGYZbmfkXrLAalGWqMQX32xsODTl1Ushj8HBKuAr5avV2/t2JEnXWEirtKL+Sar9 4Sv0KYKsLnXHqFGPaKEcjshoSESRb+QNIW0Nieq1iie2dzne+s2KLGhMaZVnk6JSujr3 SLww== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=F9nVmxbxhPUjXlAFgxWdPottc/POpyAnJKeZJvdJb3Q=; b=QemadDMPwANQifbO4+RxC3dlgF4fdEU9f36FLZhfXzRU00Zttk24YcmArwB8EVGnbg 7j3wLEHzDXrkcXyzkow7AQrQVOfFQABTxNurNXWWDFHeKG+TLrcAjcsbI+/LA+zzzP+w UHsbETeHkz0zJeuFJLaYnQrDPYQOqdRnvViDrCpIaO7oOj3HNroiVLMzZ25EhYF1Ar5S pGTOBIdieLVk+gfnkr1UgmCY/amcuQ9haDfGIZsXBT0LNjeju9sRK4h+/s88elQ8uvl7 E3r8CcmXW6mKq2G8YPrXSOiiX/uTp7NWhFPjsQACKoQFfhsHhebGQNqanC4EUMTgxmHi 9Yfw== X-Gm-Message-State: AOAM533u0lQv0RFSNQeCp02s24wIt7k5jivUSwSh/8ZlA2NgIH2C2skz endCmYkkVGgNvNqSO7bU4k6gFJzL8mc= X-Google-Smtp-Source: ABdhPJzROlR9JfnWELD1llXgexuPYrFMoAc1dOTyPtjP64jGm4kWCWLf8hy56AAM4zb4yA/N6eu63g== X-Received: by 2002:a05:6512:b11:b0:474:2b91:99c4 with SMTP id w17-20020a0565120b1100b004742b9199c4mr4252868lfu.347.1652464770749; Fri, 13 May 2022 10:59:30 -0700 (PDT) Received: from [192.168.2.145] (109-252-137-244.dynamic.spd-mgts.ru. [109.252.137.244]) by smtp.googlemail.com with ESMTPSA id b20-20020a05651c099400b0024f3d1dae82sm527639ljq.10.2022.05.13.10.59.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 13 May 2022 10:59:30 -0700 (PDT) Message-ID: Date: Fri, 13 May 2022 20:59:29 +0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [PATCH v4 3/3] iio: light: Add support for ltrf216a sensor Content-Language: en-US To: Shreeya Patel , jic23@kernel.org, lars@metafoo.de, robh+dt@kernel.org, Zhigang.Shi@liteon.com, krisman@collabora.com Cc: linux-iio@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, kernel@collabora.com, alvaro.soliverez@collabora.com References: <20220511094024.175994-1-shreeya.patel@collabora.com> <20220511094024.175994-4-shreeya.patel@collabora.com> <88b33ada-e997-05e9-f555-b9c1ed369fb7@collabora.com> From: Dmitry Osipenko In-Reply-To: <88b33ada-e997-05e9-f555-b9c1ed369fb7@collabora.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org 13.05.2022 16:40, Shreeya Patel пишет: > Also, why would we want to do a SW reset here? > > In the datasheet, I could see the following steps to enable the sensor > Supply VDD to Sensor (Sensor in Standby Mode) ---> Wait 100 ms (min) - > initial startup time > ---> I2C Command (Write) To enable sensor to Active Mode For example, if you'll do kexec from other kernel, say downstream kernel, then the h/w state is undetermined for us. It's a common problem with downstream drivers that they rely on a specific state left from bootloader, which is often unacceptable for upstream. If we'll do the SW reset on probe, then we'll bring h/w into the predictable state and won't depend on state left from bootloader or anything else that touched h/w before us.