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=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED,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 E1757C4321D for ; Fri, 24 Aug 2018 15:54:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 844F7208B2 for ; Fri, 24 Aug 2018 15:54:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 844F7208B2 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=collabora.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727770AbeHXT3w (ORCPT ); Fri, 24 Aug 2018 15:29:52 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:58466 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726268AbeHXT3w (ORCPT ); Fri, 24 Aug 2018 15:29:52 -0400 Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: eballetbo) with ESMTPSA id 09E2727DD2A From: Enric Balletbo i Serra To: linux-kernel@vger.kernel.org, robert.jarzmik@free.fr, daniel.thompson@linaro.org, lee.jones@linaro.org Cc: kernel@collabora.com, heiko@sntech.de, linux-pwm@vger.kernel.org, linux-fbdev@vger.kernel.org, Thierry Reding , Bartlomiej Zolnierkiewicz , dri-devel@lists.freedesktop.org, Jingoo Han Subject: [PATCH] backlight: pwm_bl: Fix brightness levels for non-DT case. Date: Fri, 24 Aug 2018 17:54:02 +0200 Message-Id: <20180824155402.2822-1-enric.balletbo@collabora.com> X-Mailer: git-send-email 2.18.0 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit '88ba95bedb79 ("backlight: pwm_bl: Compute brightness of LED linearly to human eye")' allows the possibility to compute a default brightness table when there isn't the brightness-levels property in the DT. Unfortunately the changes made broke the pwm backlight for the non-DT boards. Usually, the non-DT boards don't pass the brightness levels via platform data, instead, they set the max_brightness in their platform data and the driver calculates the level without a table. The ofending patch assumed that when there is no brightness levels table we should create one, but this is clearly wrong for the non-DT case. After this patch the code handles the DT and the non-DT case taking in consideration also if max_brightness is set or not. The default table is only created when neither, brightness-levels and max_brightness, are set. The patch also fixes another issue found by Robert. Before this patch looks like a division by 0 was possible when state.period returned 0 by pwm_get_state(). This is because pwm_get_state() was called before pwm_apply_args() so state.period was not initialized. The patch moves the pwm_apply_args() call before any call to pwm_get_state(). Fixes: '88ba95bedb79 ("backlight: pwm_bl: Compute brightness of LED linearly to human eye")' Reported-by: Robert Jarzmik Signed-off-by: Enric Balletbo i Serra --- drivers/video/backlight/pwm_bl.c | 50 ++++++++++++++++++++++++-------- 1 file changed, 38 insertions(+), 12 deletions(-) diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c index bdfcc0a71db1..19770f7bffe4 100644 --- a/drivers/video/backlight/pwm_bl.c +++ b/drivers/video/backlight/pwm_bl.c @@ -539,7 +539,33 @@ static int pwm_backlight_probe(struct platform_device *pdev) dev_dbg(&pdev->dev, "got pwm for backlight\n"); - if (!data->levels) { + /* + * FIXME: pwm_apply_args() should be removed when switching to + * the atomic PWM API. + */ + pwm_apply_args(pb->pwm); + + if (data->levels) { + /* + * For the DT case, only when brightness levels is defined + * data->levels is filled. For the non-DT case, data->levels + * can come from platform data, however is not usual. + */ + for (i = 0; i <= data->max_brightness; i++) { + if (data->levels[i] > pb->scale) + pb->scale = data->levels[i]; + + pb->levels = data->levels; + } + } else if (!data->max_brightness) { + /* + * If no brightness levels are provided and max_brightness is + * not set, use the default brightness table. For the DT case, + * max_brightness is set to 0 when brightness levels is not + * specified. For the non-DT case, max_brightness is usually + * set to some value. + */ + /* Get the PWM period (in nanoseconds) */ pwm_get_state(pb->pwm, &state); @@ -550,21 +576,21 @@ static int pwm_backlight_probe(struct platform_device *pdev) "failed to setup default brightness table\n"); goto err_alloc; } - } - for (i = 0; i <= data->max_brightness; i++) { - if (data->levels[i] > pb->scale) - pb->scale = data->levels[i]; + for (i = 0; i <= data->max_brightness; i++) { + if (data->levels[i] > pb->scale) + pb->scale = data->levels[i]; - pb->levels = data->levels; + pb->levels = data->levels; + } + } else { + /* + * That only happens for the non-DT case, where platform data + * sets the max_brightness value. + */ + pb->scale = data->max_brightness; } - /* - * FIXME: pwm_apply_args() should be removed when switching to - * the atomic PWM API. - */ - pwm_apply_args(pb->pwm); - /* * The DT case will set the pwm_period_ns field to 0 and store the * period, parsed from the DT, in the PWM device. For the non-DT case, -- 2.18.0