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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 4DF46C43381 for ; Sat, 16 Feb 2019 22:03:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 13C3421B1C for ; Sat, 16 Feb 2019 22:03:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733271AbfBPWDO (ORCPT ); Sat, 16 Feb 2019 17:03:14 -0500 Received: from mail-ed1-f67.google.com ([209.85.208.67]:36998 "EHLO mail-ed1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727057AbfBPWDO (ORCPT ); Sat, 16 Feb 2019 17:03:14 -0500 Received: by mail-ed1-f67.google.com with SMTP id m12so10719260edv.4 for ; Sat, 16 Feb 2019 14:03:12 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=6k7OWEmDF+10Mf8UcQUw4WI5cx+wInndK3Oe9GjJUuQ=; b=q0wY34Uv1AHmw1sL2XOpAUOSj2fm/igkaNIZnrQgUKkda+1hBt+IzrTEg8bB0iE0n7 ES5BpBWMxHz3SllG+a4UvC8g5XKX6eGNpmPSSkoHcW0h0ufz9Ku/SjEY1/RUZ2iiG61v 81DGBxhS9DFnsAFO9UadzFCMbRVNRgwR9jEEuSyRKI5uzJ0y65bTyC6eqvFk/07cxd46 DrOTJpcLV5MSJ78B+Hoj0DSYtYyCkyx3TpwkMtw8x0kJ3hyg6rT2DkFr/8ToHdnkqUJE 77CUnWmt/U2v2FvbVpeJ68rCe9mL9h6h2x+I6ocRJzJvJeeV4aCk9CXXhqw2AHhBLKpq W+wQ== X-Gm-Message-State: AHQUAuawK5GMygVdkRHNT99p6VnKExoPBq34gntXzs2zhUwVLAmkG5HU GC7v7x6q1dcLw7iaUJkKAJZ9ew== X-Google-Smtp-Source: AHgI3IZe6/SfxoUe9rro3qp3KXaNDWcmQtLuLinpGtNIn1z0zIvlZryrhyU0UhvasG/WypN4PAaJtg== X-Received: by 2002:a17:906:3719:: with SMTP id d25mr11086521ejc.142.1550354591801; Sat, 16 Feb 2019 14:03:11 -0800 (PST) Received: from localhost.localdomain ([2001:678:814:68:8573:4f61:f765:5d7e]) by smtp.gmail.com with ESMTPSA id k26sm2059486ejv.63.2019.02.16.14.03.10 (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Sat, 16 Feb 2019 14:03:11 -0800 (PST) Subject: Re: [PATCH v2 1/2] leds: Add Intel Cherry Trail Whiskey Cove PMIC LEDs To: Jacek Anaszewski , Pavel Machek Cc: Yauhen Kharuzhy , linux-kernel@vger.kernel.org, linux-leds@vger.kernel.org References: <92cf09b8-726d-4f1b-94ba-368a66af2246@redhat.com> <2b6faaa5-b21e-a512-de7d-ca21be5045fc@gmail.com> <20190214230307.GA17358@amd> <2a5e2002-e5f1-6da3-8a43-317801b69657@redhat.com> <3d5407a7-9458-f071-a1d5-511b09678e20@gmail.com> <87a21c4e-8e5e-c180-2ff3-eb8170746e71@redhat.com> <80971bc3-1193-83ed-913a-12f6217016c8@gmail.com> <8a263266-a41f-c916-e990-02d04de9b5d0@gmail.com> <20190216193727.GA14305@amd> <2d5c6f50-c41f-655c-ab03-0c66aa911a27@gmail.com> From: Hans de Goede Message-ID: Date: Sat, 16 Feb 2019 23:03:08 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <2d5c6f50-c41f-655c-ab03-0c66aa911a27@gmail.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 2/16/19 10:54 PM, Jacek Anaszewski wrote: > On 2/16/19 8:37 PM, Pavel Machek wrote: >> Hi! >> >>>>>>> I think that should work fine, which means that we can use the timer and >>>>>>> pattern trigger support for the blinking and breathing modes. >>>>>>> >>>>>>> That still leaves the switching between user and hw-control modes, >>>>>>> as discussed the hw-controlled mode could be modelled as a new "hardware" >>>>>>> trigger, but then we cannot choose between on/blink/breathing when >>>>>>> in hw-controlled mode. As Pavel mentioned, that would require some >>>>>>> sort of composed trigger, where we have both the hardware and >>>>>>> timer triggers active for example. >>>>>>> >>>>>>> I think it might be easier to just allow turning on/off the hardware >>>>>>> control mode through a special "hardware_control" sysfs attribute and >>>>>>> then use the existing timer and pattern triggers for blinking / breathing. >>>>>> >>>>>> Pattern trigger exposes pattern file by default and hw_pattern if >>>>>> pattern_set/get ops are provided. Writing them enables software and >>>>>> hardware pattern respectively. >>>>> >>>>> This is not about software vs hardware pattern. >>>>> >>>>> There are 2 *orthogonal*, separate problems/challenges with this LED controller: >>>>> >>>>> 1) It has hardware blinking and breathing, as discussed this can be >>>>> controlled through the timer and pattern triggers, so this problem >>>>> is solved. >>>>> >>>>> 2) It has 2 operating modes: >>>>> >>>>> a) Automatic/hardware controlled, in this mode the LED is turned >>>>> off or on (where on can be continues on, blinking or breathing) >>>>> by the hardware itself, when in this mode we / userspace is not >>>>> in control of the LED >>>>> >>>>> b) Manual/user controlled mode, in this mode we / userspace can >>>>> control of the LED. >>>>> >>>>> Currently there is no API in the ledclass to switch a LED from >>>>> automatic controlled to user controlled and back, This is what >>>>> the proposed hardware trigger was for, to switch to automatic >>>>> mode. A problem with this is that we still want to be able >>>>> to chose between continues on, blinking or breathing (when on), >>>>> configure the max brightness, etc. >>>> >>>> Yes, we do have the API to switch a LED from automatic (hardware >>>> accelerated) control to software control and back. This is pattern >>>> trigger, which exposes two files for setting pattern: pattern >>>> and hw_pattern. Writing pattern file switches the device to software >>>> control mode and writing hw_pattern switches it to the hardware control, >>>> with the possibility of defining device specific ABI syntax to enable >>>> particular pattern (blinking, breathing or event permanently on >>>> in case of this device). >>> >>> OK, I see. So we would use the hw_pattern for this and the driver >>> would implement the pattern_set led_classdev callback. >>> >>> The pattern_set callback would then expect 6 brightness/time tuples >>> with the following meaning for the time part of each tupple >>> >>> tupple0: charging blinking_on_time >>> tupple1: charging blinking_off_time >>> tupple2: charging breathing_time >>> tupple3: manual blinking_on_time >>> tupple4: manual blinking_off_time >>> tupple5: manual breathing_time >>> >>> Where only the times in tupple 0-2; or the times in 3-5 can be >>> non-zero. Having non zero times for both some charging and some >>> manual values is not allowed. >>> >>> If a breathing time is set, none of the other times may be non >>> 0. If blinkig_on and blinking_off are used then breathing_time >>> must be 0. >>> >>> When configured to blink then blinking_off must be either 0 >>> (continuously on); or it must be the same as blinking_on. >>> >>> >>> I believe this will work, does this sound ok to you ? >> >> I don't pretend to fully understand it, _but_ hw_pattern should really >> describe the pattern LED should do, not whether it reacts to charging >> or not. > > This is hardware specific and is supposed to have dedicated ABI > documentation. There's no reason to introduce new mechanisms when > existing ones fit. It will still describe a pattern but activated > on some condition. Right, but we can control the condition, so either we need to make the condition part of the pattern as in my recent proposal with: tupple0: charging blinking_on_time tupple1: charging blinking_off_time tupple2: charging breathing_time tupple3: manual blinking_on_time tupple4: manual blinking_off_time tupple5: manual breathing_time As hw_pattern ABI; or we need to add an extra sysfs file to set the condition. So do you prefer the driver to code the condition into the hw_pattern (see above); or do you prefer a separate sysfs attribute for the condition? Regards, Hans