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 1B6DDC433EF for ; Mon, 14 Feb 2022 22:59:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232068AbiBNW7J (ORCPT ); Mon, 14 Feb 2022 17:59:09 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:60302 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232056AbiBNW7H (ORCPT ); Mon, 14 Feb 2022 17:59:07 -0500 Received: from mail-ed1-x531.google.com (mail-ed1-x531.google.com [IPv6:2a00:1450:4864:20::531]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 58ACE1901A6 for ; Mon, 14 Feb 2022 14:58:58 -0800 (PST) Received: by mail-ed1-x531.google.com with SMTP id h18so7013629edb.7 for ; Mon, 14 Feb 2022 14:58:58 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=H4CDzrFaAIRXP+JfJQjZSpyvl+auCY5ZKASrSIHcfZ4=; b=g1eWBAr03pbHIGky/Et9stEsa62hM8KOUIVkJ/UAyGbCj4E+TeHxDAH3ngnjFzbGfy 6KPQbUeolripHdS/5FHHM9Osf86vxMO7KIsfUjlLd1M3dNyM0u8fmJH+j+mm3iJ7z63G JR5bLt0DPZE2syU6n0PxTOgFYdHlbSn8G6gXjktIi3ecNeuPuQWXqQTOZ6pD2qS1EnUj 5CI5MEwdruQArTTBNk5mEiO2WdgEek1emiOymwL1PvsONdPEK3OOEIaEqvwcIFHKrrFr 4JHZGQ3/Gfz/G39IRSC2r0IejJFYpkNCwItA4+7Y1kGBMvRC/fc9ZY7Fwo/zsr8YvW0o 1rqg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=H4CDzrFaAIRXP+JfJQjZSpyvl+auCY5ZKASrSIHcfZ4=; b=GigqJoL78N/V6AlBDt+34VLICaPBiTBHEkEIbDJue2Xuiz5M7Vk2aB+kDLxpZTGutz CTcWMuNlgV77Do8JrgJ9kqM/dRcYfeMK3riVOzYvUZsWEV3G4vFX78lWT+mI+VOAl7Ks WHwwFOwo3u9fn+OvKnB9lik2pmhFf0ARdh6/FXT7X3bCoAqlj0OIuMMq20DHvaSOnWOR /BqhW+Nhl0NvuKGho6HKwMLRmNMk6KQ9VsTrYUZDOI/qhj+q3qMWXQP/0HDIb6dZyxdh nGxlKpz3d4JOsMUQ/nCixSCIw4wBnAO/cnPppaflg6qia2jgjBeEkpPuzevVlCfArCA6 40cQ== X-Gm-Message-State: AOAM531/hXgJv5FjtSp9bXtXpgvsbPO4+C8OeAYr6ZkWv2W3a2AmcCfi +LCFBHF5p25uY7msxLAJ1tV/K0ijEqy6uwSLJMSuDQ== X-Google-Smtp-Source: ABdhPJwpXtBphXPJ50QihP13rNz4U0amvRgAmy4aDk1Wwxy0Bg+4yuTFVEPXPDcZi9Valn6eEkT1vrL25RQAh8jRaLY= X-Received: by 2002:a05:6402:50d4:: with SMTP id h20mr1175034edb.90.1644879536587; Mon, 14 Feb 2022 14:58:56 -0800 (PST) MIME-Version: 1.0 References: <20220211023008.3197397-1-wonchung@google.com> In-Reply-To: From: Won Chung Date: Mon, 14 Feb 2022 14:58:44 -0800 Message-ID: Subject: Re: [PATCH v6] ACPI: device_sysfs: Add sysfs support for _PLD To: "Rafael J. Wysocki" Cc: Len Brown , Heikki Krogerus , Benson Leung , Prashant Malani , ACPI Devel Maling List , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 14, 2022 at 12:30 PM Won Chung wrote: > > On Mon, Feb 14, 2022 at 11:12 AM Rafael J. Wysocki wrote: > > > > On Fri, Feb 11, 2022 at 3:30 AM Won Chung wrote: > > > > > > When ACPI table includes _PLD fields for a device, create a new > > > directory (pld) in sysfs to share _PLD fields. > > > > This version of the patch loos better to me, but I'm not sure if it > > goes into the right direction overall. > > > > > Currently without PLD information, when there are multiple of same > > > devices, it is hard to distinguish which device corresponds to which > > > physical device in which location. For example, when there are two Type > > > C connectors, it is hard to find out which connector corresponds to the > > > Type C port on the left panel versus the Type C port on the right panel. > > > > So I think that this is your primary use case and I'm wondering if > > this is the best way to address it. > > > > Namely, by exposing _PLD information under the ACPI device object, > > you'll make user space wanting to use that information depend on this > > interface, but the problem is not ACPI-specific (inevitably, it will > > appear on systems using DT, sooner or later) and making the user space > > interface related to it depend on ACPI doesn't look like a perfect > > choice. > > > > IOW, why don't you create a proper ABI for this in the Type C > > subsystem and expose the information needed by user space in a generic > > way that can be based on the _PLD information on systems with ACPI? > > Hi Rafael, > > Thank you for the review. > > I was thinking that _PLD info is specific to ACPI since it is part of > the ACPI table. Could you explain a little bit more on why you think > exposing _PLD fields is not an ACPI-specific problem? Hi Rafael again, Sorry for the silly question here. I misunderstood your comment a bit, but I talked to Benson and Prashant for clarification. I understand now what you mean by it is not an ACPI-specific problem and exposing PLD would depend on ACPI. > > I gave an example of how _PLD fields can be used for specifying Type C > connectors, but it is not Type C specific. For Chrome OS, we plan to > initially add PLD to not only Type C connectors but also USB port > devices (including Type C and Type A). Also, PLD can be used in the > future for describing other types of ports too like HDMI. (Benson and > Prashant, please correct or add if I am wrong or missing some > information) Maybe my commit message was not detailed enough.. > > I am also curious what Heikki thinks about this. Heikki, can you take > a look and share your thoughts? I am still curious what you and Heikki think about this since it may not be a Type C specific issue. We can start from adding generic location info to Type C subsystem first, as you suggested, then consider how to do the same for USB devices and Type A ports afterwards. I would appreciate sharing any thoughts or feedback. Thank you very much! Won > > Thank you, > Won