From patchwork Fri Aug 24 15:54:02 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Enric Balletbo i Serra X-Patchwork-Id: 10576497 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 77EBB174A for ; Mon, 27 Aug 2018 07:35:02 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5EC34296EA for ; Mon, 27 Aug 2018 07:35:02 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 51507297D4; Mon, 27 Aug 2018 07:35:02 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED,UNPARSEABLE_RELAY autolearn=ham version=3.3.1 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id C0BFD296EA for ; Mon, 27 Aug 2018 07:35:01 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 28CFE6E19F; Mon, 27 Aug 2018 07:34:45 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from bhuna.collabora.co.uk (bhuna.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e3e3]) by gabe.freedesktop.org (Postfix) with ESMTPS id C1AC36E709 for ; Fri, 24 Aug 2018 15:54:37 +0000 (UTC) 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 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 X-Mailman-Approved-At: Mon, 27 Aug 2018 07:34:43 +0000 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-pwm@vger.kernel.org, linux-fbdev@vger.kernel.org, Bartlomiej Zolnierkiewicz , Jingoo Han , dri-devel@lists.freedesktop.org, Thierry Reding , kernel@collabora.com MIME-Version: 1.0 Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" X-Virus-Scanned: ClamAV using ClamSMTP 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 Tested-by: Robert Jarzmik Acked-by: Daniel Thompson --- 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,