{"id":807292,"url":"http://patchwork.ozlabs.org/api/1.2/patches/807292/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-pwm/patch/20170829204002.8663-1-dbasehore@chromium.org/","project":{"id":38,"url":"http://patchwork.ozlabs.org/api/1.2/projects/38/?format=json","name":"Linux PWM development","link_name":"linux-pwm","list_id":"linux-pwm.vger.kernel.org","list_email":"linux-pwm@vger.kernel.org","web_url":"","scm_url":"","webscm_url":"","list_archive_url":"","list_archive_url_format":"","commit_url_format":""},"msgid":"<20170829204002.8663-1-dbasehore@chromium.org>","list_archive_url":null,"date":"2017-08-29T20:40:02","name":"[v2] pwm_bl: Fix overflow condition","commit_ref":null,"pull_url":null,"state":"superseded","archived":false,"hash":"f422623ac38a246d5dc4859e08848af63b1c858d","submitter":{"id":20364,"url":"http://patchwork.ozlabs.org/api/1.2/people/20364/?format=json","name":"dbasehore .","email":"dbasehore@chromium.org"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/linux-pwm/patch/20170829204002.8663-1-dbasehore@chromium.org/mbox/","series":[{"id":469,"url":"http://patchwork.ozlabs.org/api/1.2/series/469/?format=json","web_url":"http://patchwork.ozlabs.org/project/linux-pwm/list/?series=469","date":"2017-08-29T20:40:02","name":"[v2] pwm_bl: Fix overflow condition","version":2,"mbox":"http://patchwork.ozlabs.org/series/469/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/807292/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/807292/checks/","tags":{},"related":[],"headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@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=linux-pwm-owner@vger.kernel.org;\n\treceiver=)","ozlabs.org;\n\tdkim=fail reason=\"signature verification failed\" (1024-bit key;\n\tunprotected) header.d=chromium.org header.i=@chromium.org\n\theader.b=\"Di2n1d+z\"; dkim-atps=neutral"],"Received":["from vger.kernel.org (vger.kernel.org [209.132.180.67])\n\tby ozlabs.org (Postfix) with ESMTP id 3xhgVv5zHBz9s9Y\n\tfor ;\n\tWed, 30 Aug 2017 06:40:07 +1000 (AEST)","(majordomo@vger.kernel.org) by vger.kernel.org via listexpand\n\tid S1751263AbdH2UkH (ORCPT );\n\tTue, 29 Aug 2017 16:40:07 -0400","from mail-pf0-f179.google.com ([209.85.192.179]:34327 \"EHLO\n\tmail-pf0-f179.google.com\" rhost-flags-OK-OK-OK-OK) by vger.kernel.org\n\twith ESMTP id S1750909AbdH2UkG (ORCPT\n\t); Tue, 29 Aug 2017 16:40:06 -0400","by mail-pf0-f179.google.com with SMTP id l87so3555121pfj.1\n\tfor ; Tue, 29 Aug 2017 13:40:06 -0700 (PDT)","from exogeni.mtv.corp.google.com\n\t([2620:0:1000:1600:211e:5908:95bc:4888])\n\tby smtp.gmail.com with ESMTPSA id\n\tg20sm5960883pfg.138.2017.08.29.13.40.04\n\t(version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128);\n\tTue, 29 Aug 2017 13:40:05 -0700 (PDT)"],"DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/relaxed;\n\td=chromium.org; s=google;\n\th=from:to:cc:subject:date:message-id;\n\tbh=q/ueOxF+k/1dzzjCf5iQwWGuTGQK2DxIgpbLeCQntk8=;\n\tb=Di2n1d+zQ8ZLEqiIVPh8D/ZT2iENq7BQGZ2jjatIp18RkVxJaQfkn9SPOwNkjhiS/0\n\tiLFJQIVXkdfPPp15bMWQd1AJYDY6uRXA1oBuwTfzj5ZnyDksAYAMY9kGiAesulCwnlv1\n\tT/sObyBiOjG+iZhje39SOTBwSU7K5fvkqLKYE=","X-Google-DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/relaxed;\n\td=1e100.net; s=20161025;\n\th=x-gm-message-state:from:to:cc:subject:date:message-id;\n\tbh=q/ueOxF+k/1dzzjCf5iQwWGuTGQK2DxIgpbLeCQntk8=;\n\tb=HqFdBOmhERt9dZNIi3wMECGOf96BRDlWUyTUbDcs+EQ7jBoyixntzb/P66PLQDeJox\n\tegTOVQeGNssd6u3tbU4SG0MjC45vGIx0FPbDK9MXETh8VxT/VlsnajY5gYOdDwD2V/aC\n\thvwpIikPUMzbSUC7PfoJxUAm3w53bbOBrDFEnYyCKtVsn2SDne818219qR2YCZXqc78k\n\tJAr/KZyHkDWSiHkTxeslaWFf38H1o7XHMTYwXLfB1j7GkUrH0dPIKkJGrZKZV1cuymtf\n\tZ8Rc4PGNFwXYIHEXKRiRMQEaBnYq93VNC+D9oVFXVu8GucyGk0baw9ErLNKdysRIDLkd\n\tdGsA==","X-Gm-Message-State":"AHYfb5gJtMChc9buwn3ygIj/ZcSQwZvd/onaVb/E2qF/N2g9T3xERISK\n\tjjKUciZ+jtVtnw/L","X-Received":"by 10.99.38.65 with SMTP id m62mr1536495pgm.226.1504039206072;\n\tTue, 29 Aug 2017 13:40:06 -0700 (PDT)","From":"Derek Basehore ","To":"linux-kernel@vger.kernel.org","Cc":"thierry.reding@gmail.com, jingoohan1@gmail.com,\n\tlee.jones@linaro.org, briannorris@chromium.org,\n\tlinux-pwm@vger.kernel.org, Derek Basehore ","Subject":"[PATCH v2] pwm_bl: Fix overflow condition","Date":"Tue, 29 Aug 2017 13:40:02 -0700","Message-Id":"<20170829204002.8663-1-dbasehore@chromium.org>","X-Mailer":"git-send-email 2.14.1.342.g6490525c54-goog","Sender":"linux-pwm-owner@vger.kernel.org","Precedence":"bulk","List-ID":"","X-Mailing-List":"linux-pwm@vger.kernel.org"},"content":"This fixes an overflow condition that can happen with high max\nbrightness and period values in compute_duty_cycle. This fixes it by\nusing a 64 bit variable for computing the duty cycle.\n\nChange-Id: I745c67c7a24740316d13eaf1be74248ea2249353\nSigned-off-by: Derek Basehore \n---\n drivers/video/backlight/pwm_bl.c | 7 +++++--\n 1 file changed, 5 insertions(+), 2 deletions(-)","diff":"diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c\nindex 76311ec5e400..5ccc8e34b7a6 100644\n--- a/drivers/video/backlight/pwm_bl.c\n+++ b/drivers/video/backlight/pwm_bl.c\n@@ -88,14 +88,17 @@ static void pwm_backlight_power_off(struct pwm_bl_data *pb)\n static int compute_duty_cycle(struct pwm_bl_data *pb, int brightness)\n {\n \tunsigned int lth = pb->lth_brightness;\n-\tint duty_cycle;\n+\tu64 duty_cycle;\n \n \tif (pb->levels)\n \t\tduty_cycle = pb->levels[brightness];\n \telse\n \t\tduty_cycle = brightness;\n \n-\treturn (duty_cycle * (pb->period - lth) / pb->scale) + lth;\n+\tduty_cycle *= pb->period - lth;\n+\tdo_div(duty_cycle, pb->scale);\n+\n+\treturn duty_cycle + lth;\n }\n \n static int pwm_backlight_update_status(struct backlight_device *bl)\n","prefixes":["v2"]}