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=-2.9 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 7F0CCC43613 for ; Mon, 24 Jun 2019 20:31:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 44E1320663 for ; Mon, 24 Jun 2019 20:31:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="OerfV0sn" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731780AbfFXUbV (ORCPT ); Mon, 24 Jun 2019 16:31:21 -0400 Received: from mail-pl1-f195.google.com ([209.85.214.195]:44831 "EHLO mail-pl1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726393AbfFXUbV (ORCPT ); Mon, 24 Jun 2019 16:31:21 -0400 Received: by mail-pl1-f195.google.com with SMTP id t7so7525750plr.11 for ; Mon, 24 Jun 2019 13:31:20 -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=p8eKR4sWGzU8LALqN+Rywpmmy+C9BMm/CB6qnIMC0UI=; b=OerfV0snZfWTKFe6g+LZSlNlk+hlaRZTYdkXi6xFzubIfsuYRqrR478es590r/uipG Za9cOfVOlS/Tx8biMdxBPavuRBtuFpD5DqsfSl4Frr5uGAgXHd9EfJPHv7PHPKGz5ykf Ha81o5GREDJwrbSfWGjsmCtO9Dqm7iWDvuM8g= 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=p8eKR4sWGzU8LALqN+Rywpmmy+C9BMm/CB6qnIMC0UI=; b=uoAKWJcb8WpiY5Ure2YYXNAN7tes3Ez8IWkl1vK5kW//dHKujg6FsZHPGCM0lH4e59 /y3Rpnt/C6bZKbJ+Zxuvig/lOXZ7PBIKHTZqd/jpcP4gg/ztVooIHf+e0nqdP6SNwqYm vwdKYrnKoxkdUk855dF2OkFvt3WNwOWXnbzl7nBc81wld06QwSYMUMnFeE9SqtSwJMLE QNlfP/0ogMIv0jZL1B6jRC3SrtN1F3I9JI+S6Px8Cs+LxuYMoZCf3v4SBssdT2O22jrm Ns+IsanpNSDG7d2hGq3aR5Gd9KJLDWX9y0tygZdPA5cSkwBuZzVZ6T3x2tmwNFlMn99U cUUQ== X-Gm-Message-State: APjAAAWsWhXqftlg7mzRQ7T5sawE/+OOi5p8ta4X29s9yO46gJx/zOuF 5Pcqn2J/T8emsWMsIIHDqBcIBA== X-Google-Smtp-Source: APXvYqzBKihWAttr4Rykcb5BT7S4M6tWgTs4LN43nmmOkYIKYPwMKpzMISvKirmoiIp5hny8kMFQzQ== X-Received: by 2002:a17:902:d916:: with SMTP id c22mr20031582plz.195.1561408280395; Mon, 24 Jun 2019 13:31:20 -0700 (PDT) Received: from localhost ([2620:15c:202:1:75a:3f6e:21d:9374]) by smtp.gmail.com with ESMTPSA id u128sm15650127pfu.26.2019.06.24.13.31.19 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 24 Jun 2019 13:31:19 -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 v2 0/4] backlight: Expose brightness curve type through sysfs Date: Mon, 24 Jun 2019 13:31:09 -0700 Message-Id: <20190624203114.93277-1-mka@chromium.org> X-Mailer: git-send-email 2.22.0.410.gd8fdbe21b5-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 | 21 +++++++++++ drivers/video/backlight/pwm_bl.c | 35 ++++++++++++++++++- include/linux/backlight.h | 10 ++++++ 5 files changed, 99 insertions(+), 1 deletion(-) create mode 100644 Documentation/ABI/testing/sysfs-class-backlight -- 2.22.0.410.gd8fdbe21b5-goog