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=-5.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 40FF9C433FF for ; Wed, 7 Aug 2019 20:15:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0C7C92199C for ; Wed, 7 Aug 2019 20:15:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="RwoY0vyV" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389227AbfHGUPe (ORCPT ); Wed, 7 Aug 2019 16:15:34 -0400 Received: from mail-pl1-f195.google.com ([209.85.214.195]:45894 "EHLO mail-pl1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387985AbfHGUPd (ORCPT ); Wed, 7 Aug 2019 16:15:33 -0400 Received: by mail-pl1-f195.google.com with SMTP id y8so302841plr.12 for ; Wed, 07 Aug 2019 13:15:33 -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=RU+mCl+d15cBnmP6BMoJqIyEACy478kUYuCNnNZJiqw=; b=RwoY0vyVibrSFxjnucYfjp+aWRh2NgUEtgqFYjY8w08e7aiLVLcxKn9RCWHq4b7SJk 8FUeg3lCxv6f5agtWIgt/tatmSYIRk7tQRv0RZf4BH0NKtCUnT5xLuQvXFDvXqH0W8Ui PKtctk6GL5/3C3yNzZ90bt706+jZtcmRS4NJw= 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=RU+mCl+d15cBnmP6BMoJqIyEACy478kUYuCNnNZJiqw=; b=ggaDS07O+x+MvEJ0uz5ZrbZYAP1JENqL/5cauK5B8nU7uMFsxyCwFbT0x479y9eoVr jEsMVXrb8ag+xJUDXYUKjotADfopZgJa5wVNE3Nuf0IAPklprEqLMVvFgrYkg0cvoXPU 5dQolRi8ln1yqzqU7pOAP9npBh4N/iXzryIAT4oOPP0dYP3IQy6w6dSE66a/RAoIypIy 4jmjiCtgF8mLDnkHJj3v3fwRfI47paJoRGJfsURQLIrn8zbg92O93j/iuco1Apfoy9L3 zffNg701s7kRCX5TsUNqCjQGkVjy1wfewZlTRlEKVHLA4Ve5q2L7pUc94u+o9e2SuevH Xcng== X-Gm-Message-State: APjAAAVI0bG3wIhY8+1VtWEdrTxZ93UdvClEev5UvlwI+fbnzMAVdQRS i2mcbZVS0ft4idgwy25LRg7x4w== X-Google-Smtp-Source: APXvYqzcVZwYo5rrOlwBwZoU659GCbZRYFCC2aSl+NJNpuqYHhxbX896kG9fN1cjA8EAoMnQE6+lFQ== X-Received: by 2002:a17:902:b582:: with SMTP id a2mr10103527pls.128.1565208933200; Wed, 07 Aug 2019 13:15:33 -0700 (PDT) Received: from localhost ([2620:15c:202:1:75a:3f6e:21d:9374]) by smtp.gmail.com with ESMTPSA id w197sm116457813pfd.41.2019.08.07.13.15.31 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 07 Aug 2019 13:15:32 -0700 (PDT) Date: Wed, 7 Aug 2019 13:15:28 -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 2/4] backlight: Expose brightness curve type through sysfs Message-ID: <20190807201528.GO250418@google.com> References: <20190709190007.91260-1-mka@chromium.org> <20190709190007.91260-3-mka@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190709190007.91260-3-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 12:00:05PM -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 currently is opaque > to userspace, so userspace often uses 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 the new sysfs attribute > 'scale'. The value of the attribute can be 'linear', 'non-linear' or > 'unknown'. For devices that don't provide information about the scale > of their brightness curve the value of the 'scale' attribute is 'unknown'. > > Signed-off-by: Matthias Kaehlcke Daniel (et al): do you have any more comments on this patch/series or is it ready to land? Thanks Matthias From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthias Kaehlcke Date: Wed, 07 Aug 2019 20:15:28 +0000 Subject: Re: [PATCH v3 2/4] backlight: Expose brightness curve type through sysfs Message-Id: <20190807201528.GO250418@google.com> List-Id: References: <20190709190007.91260-1-mka@chromium.org> <20190709190007.91260-3-mka@chromium.org> In-Reply-To: <20190709190007.91260-3-mka@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit 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 On Tue, Jul 09, 2019 at 12:00:05PM -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 currently is opaque > to userspace, so userspace often uses 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 the new sysfs attribute > 'scale'. The value of the attribute can be 'linear', 'non-linear' or > 'unknown'. For devices that don't provide information about the scale > of their brightness curve the value of the 'scale' attribute is 'unknown'. > > Signed-off-by: Matthias Kaehlcke Daniel (et al): do you have any more comments on this patch/series or is it ready to land? Thanks Matthias