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{ "id": 809726, "url": "http://patchwork.ozlabs.org/api/covers/809726/?format=api", "web_url": "http://patchwork.ozlabs.org/project/devicetree-bindings/cover/20170904153504.27963-1-enric.balletbo@collabora.com/", "project": { "id": 37, "url": "http://patchwork.ozlabs.org/api/projects/37/?format=api", "name": "Devicetree Bindings", "link_name": "devicetree-bindings", "list_id": "devicetree.vger.kernel.org", "list_email": "devicetree@vger.kernel.org", "web_url": "", "scm_url": "", "webscm_url": "", "list_archive_url": "", "list_archive_url_format": "", "commit_url_format": "" }, "msgid": "<20170904153504.27963-1-enric.balletbo@collabora.com>", "list_archive_url": null, "date": "2017-09-04T15:35:02", "name": "[RFC,0/2] backlight: pwm_bl: support linear brightness to human eye", "submitter": { "id": 68184, "url": "http://patchwork.ozlabs.org/api/people/68184/?format=api", "name": "Enric Balletbo i Serra", "email": "enric.balletbo@collabora.com" }, "mbox": "http://patchwork.ozlabs.org/project/devicetree-bindings/cover/20170904153504.27963-1-enric.balletbo@collabora.com/mbox/", "series": [ { "id": 1408, "url": "http://patchwork.ozlabs.org/api/series/1408/?format=api", "web_url": "http://patchwork.ozlabs.org/project/devicetree-bindings/list/?series=1408", "date": "2017-09-04T15:35:03", "name": "backlight: pwm_bl: support linear brightness to human eye", "version": 1, "mbox": "http://patchwork.ozlabs.org/series/1408/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/covers/809726/comments/", "headers": { "Return-Path": "<devicetree-owner@vger.kernel.org>", "X-Original-To": "incoming-dt@patchwork.ozlabs.org", "Delivered-To": "patchwork-incoming-dt@bilbo.ozlabs.org", "Authentication-Results": "ozlabs.org;\n\tspf=none (mailfrom) smtp.mailfrom=vger.kernel.org\n\t(client-ip=209.132.180.67; helo=vger.kernel.org;\n\tenvelope-from=devicetree-owner@vger.kernel.org; receiver=<UNKNOWN>)", "Received": [ "from vger.kernel.org (vger.kernel.org [209.132.180.67])\n\tby ozlabs.org (Postfix) with ESMTP id 3xmDTQ1m5cz9t2c\n\tfor <incoming-dt@patchwork.ozlabs.org>;\n\tTue, 5 Sep 2017 01:36:10 +1000 (AEST)", "(majordomo@vger.kernel.org) by vger.kernel.org via listexpand\n\tid S1753833AbdIDPfP (ORCPT\n\t<rfc822;incoming-dt@patchwork.ozlabs.org>);\n\tMon, 4 Sep 2017 11:35:15 -0400", "from bhuna.collabora.co.uk ([46.235.227.227]:46148 \"EHLO\n\tbhuna.collabora.co.uk\" rhost-flags-OK-OK-OK-OK) by vger.kernel.org\n\twith ESMTP id S1753748AbdIDPfP (ORCPT\n\t<rfc822; devicetree@vger.kernel.org>); Mon, 4 Sep 2017 11:35:15 -0400", "from [127.0.0.1] (localhost [127.0.0.1])\n\t(Authenticated sender: eballetbo) with ESMTPSA id C5BB7260455" ], "From": "Enric Balletbo i Serra <enric.balletbo@collabora.com>", "To": "Lee Jones <lee.jones@linaro.org>,\n\tDaniel Thompson <daniel.thompson@linaro.org>,\n\tJingoo Han <jingoohan1@gmail.com>, Richard Purdie <rpurdie@rpsys.net>,\n\tJacek Anaszewski <jacek.anaszewski@gmail.com>,\n\tPavel Machek <pavel@ucw.cz>, Rob Herring <robh+dt@kernel.org>,\n\tMark Rutland <mark.rutland@arm.com>,\n\tDoug Anderson <dianders@google.com>, \n\tBrian Norris <briannorris@google.com>, Guenter Roeck <groeck@google.com>", "Cc": "linux-leds@vger.kernel.org, devicetree@vger.kernel.org,\n\tlinux-kernel@vger.kernel.org", "Subject": "[RFC 0/2] backlight: pwm_bl: support linear brightness to human eye", "Date": "Mon, 4 Sep 2017 17:35:02 +0200", "Message-Id": "<20170904153504.27963-1-enric.balletbo@collabora.com>", "X-Mailer": "git-send-email 2.9.3", "Sender": "devicetree-owner@vger.kernel.org", "Precedence": "bulk", "List-ID": "<devicetree.vger.kernel.org>", "X-Mailing-List": "devicetree@vger.kernel.org" }, "content": "Dear all,\n\nThis patch series is a first RFC to know your opinion about implement\nsupport to create brightness levels tables dinamically. I tried to argue\nin every patch the specific reasons we think this can be interesting, to\nsumup, the idea behind these patches is be able to pass via device tree\ntwo parameters to the driver so it can calculate the brightness levels\nbased on the CIE 1931 lightness formula, which is what actually describes\nhow we perceive light.\n\nI think that at least the maths involved can be improved, and I've still\nsome doubts. With current code if you create a table with a max PWM\nvalue of 255 and 127 steps, the first numbers are repeated so I'm thinking\nthat maybe we should skip/remove the repeated values. i.e. have a table\nlike this,\n\n[0, 1, 2, 3 ... 235, 240, 245, 250, 255]\n\ninstead of\n\n[0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 2, 3 ... 235, 240, 245, 250, 255]\n\nWell, I know there are things to improve but lets see your feedback first\nbefore dedicate more time on it. The patches were tested on a couple of\ndevices but I'll test on more devices meanwhile we discuss about it.\n\nBest regards,\n\nEnric Balletbo i Serra (2):\n dt-bindings: pwm-backlight: add brightness-levels-scale property\n backlight: pwm_bl: compute brightness of LED linearly to human eye.\n\n .../bindings/leds/backlight/pwm-backlight.txt | 21 ++++\n drivers/video/backlight/pwm_bl.c | 111 +++++++++++++++++++--\n 2 files changed, 123 insertions(+), 9 deletions(-)" }