From patchwork Mon Sep 6 21:55:25 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Thomas_Wei=C3=9Fschuh?= X-Patchwork-Id: 507402 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=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, 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 5D3C9C433EF for ; Mon, 6 Sep 2021 21:57:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 31E416108D for ; Mon, 6 Sep 2021 21:57:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231256AbhIFV6b (ORCPT ); Mon, 6 Sep 2021 17:58:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48268 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229766AbhIFV6b (ORCPT ); Mon, 6 Sep 2021 17:58:31 -0400 Received: from todd.t-8ch.de (todd.t-8ch.de [IPv6:2a01:4f8:c010:41de::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 74626C061575; Mon, 6 Sep 2021 14:57:23 -0700 (PDT) From: =?utf-8?q?Thomas_Wei=C3=9Fschuh?= DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=weissschuh.net; s=mail; t=1630965441; bh=TBejuk5tqxeDF6kzvgEoVLlD9PzQKnYZHfHp2go1+m0=; h=From:To:Cc:Subject:Date:From; b=shQLHPvHG8+XyfIILO61kyyNG/BROBofAliqcMYmkCUaLfm8HZHAJviNKtZ7hMEmy DHiJe+9HFHypMP2UtGvEWf+3kxmPh/PNqAGqtVGOPpr7UbLPjKVJOobRUqoJEKMTVS 05/jvbADBFSRMZGQdtRjveq4E4vXVYzHIUKr1L0U= To: Lee Jones , Daniel Thompson , Jingoo Han , dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org Cc: =?utf-8?q?Thomas_Wei=C3=9Fschuh?= , linux-kernel@vger.kernel.org Subject: [PATCH] backlight: propagate errors from get_brightness() Date: Mon, 6 Sep 2021 23:55:25 +0200 Message-Id: <20210906215525.15418-1-linux@weissschuh.net> X-Mailer: git-send-email 2.33.0 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fbdev@vger.kernel.org backlight.h documents "struct backlight_ops->get_brightness()" to return a negative errno on failure. So far these errors have not been handled in the backlight core. This leads to negative values being exposed through sysfs although only positive values are documented to be reported. Signed-off-by: Thomas Weißschuh --- drivers/video/backlight/backlight.c | 22 +++++++++++++++++----- 1 file changed, 17 insertions(+), 5 deletions(-) base-commit: 79fad92f2e596f5a8dd085788a24f540263ef887 diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c index 537fe1b376ad..d681962f8509 100644 --- a/drivers/video/backlight/backlight.c +++ b/drivers/video/backlight/backlight.c @@ -292,10 +292,13 @@ static ssize_t actual_brightness_show(struct device *dev, struct backlight_device *bd = to_backlight_device(dev); mutex_lock(&bd->ops_lock); - if (bd->ops && bd->ops->get_brightness) - rc = sprintf(buf, "%d\n", bd->ops->get_brightness(bd)); - else + if (bd->ops && bd->ops->get_brightness) { + rc = bd->ops->get_brightness(bd); + if (rc >= 0) + rc = sprintf(buf, "%d\n", rc); + } else { rc = sprintf(buf, "%d\n", bd->props.brightness); + } mutex_unlock(&bd->ops_lock); return rc; @@ -381,9 +384,18 @@ ATTRIBUTE_GROUPS(bl_device); void backlight_force_update(struct backlight_device *bd, enum backlight_update_reason reason) { + int brightness; + mutex_lock(&bd->ops_lock); - if (bd->ops && bd->ops->get_brightness) - bd->props.brightness = bd->ops->get_brightness(bd); + if (bd->ops && bd->ops->get_brightness) { + brightness = bd->ops->get_brightness(bd); + if (brightness >= 0) + bd->props.brightness = brightness; + else + dev_warn(&bd->dev, + "Could not update brightness from device: errno = %d", + -brightness); + } mutex_unlock(&bd->ops_lock); backlight_generate_event(bd, reason); }