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=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 946C6C1975A for ; Thu, 12 Mar 2020 13:10:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6B104206BE for ; Thu, 12 Mar 2020 13:10:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=baylibre-com.20150623.gappssmtp.com header.i=@baylibre-com.20150623.gappssmtp.com header.b="AdZtKeCP" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726127AbgCLNKz (ORCPT ); Thu, 12 Mar 2020 09:10:55 -0400 Received: from mail-qk1-f194.google.com ([209.85.222.194]:46502 "EHLO mail-qk1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726385AbgCLNKy (ORCPT ); Thu, 12 Mar 2020 09:10:54 -0400 Received: by mail-qk1-f194.google.com with SMTP id f28so5953355qkk.13 for ; Thu, 12 Mar 2020 06:10:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=baylibre-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=Fw7HC8zfyv7xlZ8Y772nkRRedqdvBOfOWFl3YVWCR/U=; b=AdZtKeCPQg9PgXC0gviIyq+JosFZw/cAj9pq91dp7zf89VIQDfzUxGcjz8E8TkavhT RXxwgeNdTPjfEsKrFyHeXoXs7WFrhj9ob0zHAdnhajSny3M5b/maHxghCUkR8VcOIgg8 s7uOi1wR/QJzem+7e/rCx/FDiXmep2ZF3NmBzvwQXQZTX9kvfEW9Fl1Zpgba+BubQ0EU sFyIF4FLnctOXb1QrFeHZe455H9ZlDTzReH8Cha5blAUVyxNOr4DMlDMzccRxpGsxaLg 4+l1Ydhy9ahwwDJucHO68yg8M6y40megUBqte2rt2btM9CIDfaqWnmrbvt3Burx5y9Lg mD4Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=Fw7HC8zfyv7xlZ8Y772nkRRedqdvBOfOWFl3YVWCR/U=; b=aL67phVVV0cc/lC4OyoR0e9CyLwfuMpTMNyQ4iZaxpPWOPfRFb62kVi9gE5EE6sqyL IJ8+J5M+RdXqlluRqlyk5APQDBAcTUbSXER+4Lyej6r1w0PdF1lY6oP0sYuWt54BAdHr WSIaG4bNXcgNAE4xFs4JuTLd/IzuTkD80zpgwY/LHOucKa4o1GHHPP4TXoJuWsYIkZWY PoXhN9fDH1S9GUJl3gzmX6JFFWeZc+W/T95OudTCXxN5dEDRR/h4qAESr/1aS191PXDJ IddqusT7npNWIeH+vz5bPnE49BycnaGKsusouFSROScNZ0DRtlgQ2cZA1k3QXI0yLXS2 bXGQ== X-Gm-Message-State: ANhLgQ0KxzJwMGlLfCBH4WATqAIfCgegvkYtDbyRg3rmZ5oJnQJIpNp+ SdwoW4EVOtmNiZJsjbOUULD8K6AP8vSp2Vl2aQvxpw== X-Google-Smtp-Source: ADFU+vsmLosOjuDP68r5eZPgol6dnmqRd+ZILVuI3Tk+l4vBb9/VptFkuJxMubd5z3NSwovTdmfxm5comn6Ihs5O5vc= X-Received: by 2002:a05:620a:1362:: with SMTP id d2mr7822512qkl.120.1584018652254; Thu, 12 Mar 2020 06:10:52 -0700 (PDT) MIME-Version: 1.0 References: <20200121134157.20396-1-sakari.ailus@linux.intel.com> <20200121134157.20396-6-sakari.ailus@linux.intel.com> <20200311085555.GH5379@paasikivi.fi.intel.com> In-Reply-To: <20200311085555.GH5379@paasikivi.fi.intel.com> From: Bartosz Golaszewski Date: Thu, 12 Mar 2020 14:10:32 +0100 Message-ID: Subject: Re: [PATCH v4 5/6] at24: Support probing while off To: Sakari Ailus Cc: linux-i2c , Wolfram Sang , "Rafael J. Wysocki" , linux-acpi@vger.kernel.org, Bingbu Cao , linux-media , Chiranjeevi Rapolu , Hyungwoo Yang , Arnd Bergmann , LKML , Greg Kroah-Hartman , Rajmohan Mani , Tomasz Figa Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org =C5=9Br., 11 mar 2020 o 09:56 Sakari Ailus n= apisa=C5=82(a): > > Hi Bartosz, > > Thanks for the reply. > > On Wed, Jan 29, 2020 at 02:36:17PM +0100, Bartosz Golaszewski wrote: > > wt., 21 sty 2020 o 14:41 Sakari Ailus na= pisa=C5=82(a): > > > > > > In certain use cases (where the chip is part of a camera module, and = the > > > camera module is wired together with a camera privacy LED), powering = on > > > the device during probe is undesirable. Add support for the at24 to > > > execute probe while being powered off. For this to happen, a hint in = form > > > of a device property is required from the firmware. > > > > > > Signed-off-by: Sakari Ailus > > > --- > > > drivers/misc/eeprom/at24.c | 31 +++++++++++++++++++++---------- [snip!] > > > > > > static int at24_remove(struct i2c_client *client) > > > { > > > + bool low_power; > > > + > > > pm_runtime_disable(&client->dev); > > > - pm_runtime_set_suspended(&client->dev); > > > + low_power =3D acpi_dev_state_low_power(&client->dev); > > > > This is inconsistent. You define the low_power field in the context > > structure (BTW the name low_power is a bit vague here - without > > looking at its assignment it would make me think it's about something > > battery-related, how about 'off_at_probe'?) and instead of reusing > > The field was called probe_powered_off in v1, but I changed it to > probe_low_power (and renamed related functions etc.) based on review > comments --- for the device may not be powered off actually. > But is it actually ever low-power? What are the possible logical states of the device? If I understood correctly: it's either off or on at probe - not actually low-power. Am I missing something? In your cover letter you're writing: "These patches enable calling (and finishing) a driver's probe function without powering on the respective device on busses where the practice is to power on the device for probe." To me there's no mention of a low-power state, which makes the name 'probe_low_power' seem completely unrelated. > > this field here, you call acpi_dev_state_low_power() again. Either > > don't store the context for the life-time of the device if not > > necessary or don't call acpi_dev_state_low_power() at remove, although > > the commit message doesn't describe whether the latter is done on > > purpose. > > Right. probe-low-power property has the same effect on remove for > consistency, i.e. the device can remain in low power state during remove. > This is documented in probe_low_power field documentation in the first > patch. > Just please don't store any state if you're not using it outside of the probe() function. Bartosz