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=-2.8 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_GIT 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 32DEEC31E45 for ; Thu, 13 Jun 2019 19:43:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 073B420B7C for ; Thu, 13 Jun 2019 19:43:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="gy6E/NSd" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729081AbfFMTnc (ORCPT ); Thu, 13 Jun 2019 15:43:32 -0400 Received: from mail-pl1-f194.google.com ([209.85.214.194]:43857 "EHLO mail-pl1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728667AbfFMTnc (ORCPT ); Thu, 13 Jun 2019 15:43:32 -0400 Received: by mail-pl1-f194.google.com with SMTP id cl9so8553323plb.10 for ; Thu, 13 Jun 2019 12:43:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=i/JBzTlaIRys/4FXlOVowrLaN7Y7ioCSg9apqikje/Y=; b=gy6E/NSdOlgf6LDqxXvrrdZaWN9fZiGtU2p+2qfuTU2RRFBgGSCkswaDXP5lnek7Gt gIVtAu43gayoXBKbFHeReMDQsGHMe0OrC+LStPfMP/aB3BLgPDlqHg6jhTl5BH7TWDvR ALcClNEmwV9FnItsyQwG8b7Eyniz5DLVJMvZ8= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=i/JBzTlaIRys/4FXlOVowrLaN7Y7ioCSg9apqikje/Y=; b=MDDmNNJqNSgxtS7bQhcZZ33oSO+FfxpF1ZAxWaaCCDVzFJYAWu4Y7ArjUEAQoUj5p9 J35VkVTvsLxjJ3qY5aO0/FT/b8DbflilVSJVFQ3FE58q+8Ofo02q1aBM78NdGRG+kzDm jLoqkqSd8G9itUKcvHz9lVyKsg/FrqiqIsVsPo6Bes1NlR6OH922Vu9pQPTyWSXTZGQu yrsrEMhEVnGmxthlZKmDib51qYodjtVoa+rstlZz+QgQe6PZQZyJNHoH9vXA1BVhnSCf rAZ2GzIDyQb7iO1Gk704iV/WM1TsVl3NvI9CJgV5IXHvjyfe+sznMBrPmxilwN6wQ1E4 nsbQ== X-Gm-Message-State: APjAAAVc8/HwnWnwBhuhkz1Uqdj7Uhc+LT2D/6lbKL+I53aoc4acNolr 2jNV8u3TF4jEWLbafwOnkKafGQ== X-Google-Smtp-Source: APXvYqy985in01FdAKRYCWFmFh62RofTuNsQ+FVfIK1rCnkbbPytQd81yY4V9MCH3ohqvL1VEyDFfA== X-Received: by 2002:a17:902:21:: with SMTP id 30mr88301989pla.302.1560455011492; Thu, 13 Jun 2019 12:43:31 -0700 (PDT) Received: from localhost ([2620:15c:202:1:75a:3f6e:21d:9374]) by smtp.gmail.com with ESMTPSA id f2sm498807pgs.83.2019.06.13.12.43.30 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 13 Jun 2019 12:43:31 -0700 (PDT) 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 , Matthias Kaehlcke Subject: [PATCH 0/4] backlight: Expose brightness curve type through sysfs Date: Thu, 13 Jun 2019 12:43:22 -0700 Message-Id: <20190613194326.180889-1-mka@chromium.org> X-Mailer: git-send-email 2.22.0.rc2.383.gf4fbbf30c2-goog MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 | 32 +++++++++++++++++++ MAINTAINERS | 2 ++ drivers/video/backlight/backlight.c | 22 +++++++++++++ drivers/video/backlight/pwm_bl.c | 30 ++++++++++++++++- include/linux/backlight.h | 10 ++++++ 5 files changed, 95 insertions(+), 1 deletion(-) create mode 100644 Documentation/ABI/testing/sysfs-class-backlight -- 2.22.0.rc2.383.gf4fbbf30c2-goog