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=0.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,TVD_SUBJ_WIPE_DEBT, USER_AGENT_SANE_1 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 9B96AECE58C for ; Fri, 11 Oct 2019 10:21:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6F42521D80 for ; Fri, 11 Oct 2019 10:21:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727561AbfJKKVd (ORCPT ); Fri, 11 Oct 2019 06:21:33 -0400 Received: from mga02.intel.com ([134.134.136.20]:3286 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726585AbfJKKVd (ORCPT ); Fri, 11 Oct 2019 06:21:33 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga101.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 11 Oct 2019 03:21:22 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.67,283,1566889200"; d="scan'208";a="207400881" Received: from lahna.fi.intel.com (HELO lahna) ([10.237.72.157]) by fmsmga001.fm.intel.com with SMTP; 11 Oct 2019 03:21:19 -0700 Received: by lahna (sSMTP sendmail emulation); Fri, 11 Oct 2019 13:21:18 +0300 Date: Fri, 11 Oct 2019 13:21:18 +0300 From: Mika Westerberg To: Benjamin Tissoires Cc: Hans de Goede , Kai-Heng Feng , Jiri Kosina , You-Sheng Yang , "open list:HID CORE LAYER" , lkml Subject: Re: [PATCH] HID: i2c-hid: Remove runtime power management Message-ID: <20191011102118.GD2819@lahna.fi.intel.com> References: <20191008153829.24766-1-kai.heng.feng@canonical.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 11, 2019 at 11:27:10AM +0200, Benjamin Tissoires wrote: > Hi, > > [Adding Mika, who introduced runpm in i2c-hid] > > few questions, remarks: > > On Tue, Oct 8, 2019 at 10:26 PM Hans de Goede wrote: > > > > Hi, > > > > On 08-10-2019 17:38, Kai-Heng Feng wrote: > > > Runtime power management in i2c-hid brings lots of issues, such as: > > > - When transitioning from display manager to desktop session, i2c-hid > > > was closed and opened, so the device was set to SLEEP and ON in a short > > > period. Vendors confirmed that their devices can't handle fast ON/SLEEP > > > command because Windows doesn't have this behavior. > > > > > > - When rebooting, i2c-hid was closed, and the driver core put the device > > > back to full power before shutdown. This behavior also triggers a quick > > > SLEEP and ON commands that some devices can't handle, renders an > > > unusable touchpad after reboot. > > > > > > - Runtime power management is only useful when i2c-hid isn't opened, > > > i.e. a laptop without desktop session, which isn't that common. > > There is also one GPM-like driver that uses libinput (can't remember > from the top of my head), but you can have the i2c-hid device opened > on a vt too (with 2 finger gestures for scrolling and what not) :) > > And there is also the use case of a 2-in-1 when the laptop is in > tablet mode. In some cases, the compositor will close the inputs to > ignore the touchpad events. > > Anyway, Mika, is there any drawbacks of not having runpm on i2c-hid > devices? Maybe at the IRQ level? Nothing comes to mind except that power consumption might increase if the device is not used but if that's not an issue then no objections from my side :)