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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,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 1595EC7618F for ; Mon, 22 Jul 2019 23:59:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D7542218BE for ; Mon, 22 Jul 2019 23:59:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="BwwNgGUL" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387551AbfGVX73 (ORCPT ); Mon, 22 Jul 2019 19:59:29 -0400 Received: from mail-pg1-f194.google.com ([209.85.215.194]:41657 "EHLO mail-pg1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730693AbfGVX73 (ORCPT ); Mon, 22 Jul 2019 19:59:29 -0400 Received: by mail-pg1-f194.google.com with SMTP id x15so8081285pgg.8 for ; Mon, 22 Jul 2019 16:59:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=yKJpc6b5YDtH8HQ6uiATAFLuSozdZCVilkIngvbXM5A=; b=BwwNgGULwWCLx8dsVMfholYHHZtahSRNI4WRi8GeRE1cTEnEj7+QLHRFtS1OwD7OfL PBhCf2HLH/xHTCrVy2tXcVrzcxjy/X/9XS3xE3DB5oNwZDSgYT1w2T1voSeXQoCgP+lE YAbbno9nOKjFkhoG+ymLqQNzmX7kqXLBCtzVc= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=yKJpc6b5YDtH8HQ6uiATAFLuSozdZCVilkIngvbXM5A=; b=QfkzpF8je1blF3Z6Q+2goVUXeJw+37wN8HIp8eqUVUl5DWNYW7NAEUBO6bqN8tDvz1 AZ++EQQy+LqPTF4OjdDDrSEpOmSIRHXhCEWSPz+nz6kGYRd5kk+kqv4Xwcko8380YlTq ekxN7TiXBDi7MgPv50Iqr41S6/Rh117YG50x9JJW5CFftrpgpeVhMfbjVG9oM25Czkk3 f/tiVxeWSOoTmTKtzHO2VJTwksEUpqDHjrEh9J3U5xtHH7Dzop1z5ZpDwL662C5bDjhN VCgBicnzjDixpV8vL4/3eeJTPqwhRy5g7AoBBvQvq0MttswUuE+Gb1vunqdj1aYt+jEt sQ6Q== X-Gm-Message-State: APjAAAVsX1C34FO6c+eFWpwlZ0qlBuujTIRIk04ytflZbPbxOcM+hCTH fSkimR+Zwfd9AKtN5QrdOEMejg== X-Google-Smtp-Source: APXvYqylBuVwl7XZwxbVNxqA1DcLvAlMOG8gWbqhX7r0RR7aDWH3sQ/kfj0iiNgQmQOUzrSpDH2+kA== X-Received: by 2002:a63:4e60:: with SMTP id o32mr75155489pgl.68.1563839968519; Mon, 22 Jul 2019 16:59:28 -0700 (PDT) Received: from localhost ([2620:15c:202:1:75a:3f6e:21d:9374]) by smtp.gmail.com with ESMTPSA id f88sm40294971pjg.5.2019.07.22.16.59.27 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 22 Jul 2019 16:59:27 -0700 (PDT) Date: Mon, 22 Jul 2019 16:59:26 -0700 From: Matthias Kaehlcke To: Thierry Reding , Lee Jones , Daniel Thompson , Jingoo Han , Bartlomiej Zolnierkiewicz Cc: linux-pwm@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org, Enric Balletbo i Serra , Douglas Anderson , Brian Norris , Pavel Machek , Jacek Anaszewski Subject: Re: [PATCH v3 0/4] backlight: Expose brightness curve type through sysfs Message-ID: <20190722235926.GA250418@google.com> References: <20190709190007.91260-1-mka@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190709190007.91260-1-mka@chromium.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 09, 2019 at 12:00:03PM -0700, Matthias Kaehlcke wrote: > Backlight brightness curves can have different shapes. The two main > types are linear and non-linear curves. The human eye doesn't > perceive linearly increasing/decreasing brightness as linear (see > also 88ba95bedb79 "backlight: pwm_bl: Compute brightness of LED > linearly to human eye"), hence many backlights use non-linear (often > logarithmic) brightness curves. The type of curve is currently opaque > to userspace, so userspace often relies on more or less reliable > heuristics (like the number of brightness levels) to decide whether > to treat a backlight device as linear or non-linear. > > Export the type of the brightness curve via a new sysfs attribute. > > Matthias Kaehlcke (4): > MAINTAINERS: Add entry for stable backlight sysfs ABI documentation > backlight: Expose brightness curve type through sysfs > backlight: pwm_bl: Set scale type for CIE 1931 curves > backlight: pwm_bl: Set scale type for brightness curves specified in > the DT > > .../ABI/testing/sysfs-class-backlight | 26 ++++++++++++++ > MAINTAINERS | 2 ++ > drivers/video/backlight/backlight.c | 19 ++++++++++ > drivers/video/backlight/pwm_bl.c | 35 ++++++++++++++++++- > include/linux/backlight.h | 8 +++++ > 5 files changed, 89 insertions(+), 1 deletion(-) > create mode 100644 Documentation/ABI/testing/sysfs-class-backlight ping, any comments on v3? Thanks Matthias