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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BAEC7EB64DA for ; Tue, 4 Jul 2023 17:07:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231491AbjGDRHg (ORCPT ); Tue, 4 Jul 2023 13:07:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59948 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231482AbjGDRHf (ORCPT ); Tue, 4 Jul 2023 13:07:35 -0400 Received: from mailrelay3-1.pub.mailoutpod2-cph3.one.com (mailrelay3-1.pub.mailoutpod2-cph3.one.com [IPv6:2a02:2350:5:402::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 012D8E76 for ; Tue, 4 Jul 2023 10:07:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ravnborg.org; s=rsa1; h=in-reply-to:content-type:mime-version:references:message-id:subject:cc:to: from:date:from; bh=R1ftX/nJ28RCUlvCxqfDZHT0ym06Es3SsEj3om09Vrs=; b=mFMBx5NkiSByK1HMjoIkzQWNmb/ecgu4OOhkDtUvQth7NKdDRhm3aIp5s8eso3WdLAB+9xiBPbmSt PA3WhzFS9ZgVq2RloHgeFfgZ/NFVjPtgR+YEMQeC/6OM40w1LuQTKek+MlpIRwyDxL6tWPQAs6ZJgE VPloanifqZ0Kpn16QDQRettF7Yffput5jWae6HWTFbdQJ0O7HJCiR9EAWZAg2OvcA0CJtCElPD/h2c IEuuVxok7/fSaC2Krc7/yMkaLKGY5KaKVOIdBcI2Qckntdn8h5ZUiZFJLdCzZxdE9fXzXeToS5HZt1 2A8rIjpoUk4iTafFGT1fxcFbgp045ZQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=ravnborg.org; s=ed1; h=in-reply-to:content-type:mime-version:references:message-id:subject:cc:to: from:date:from; bh=R1ftX/nJ28RCUlvCxqfDZHT0ym06Es3SsEj3om09Vrs=; b=toRiw7qMpH7Z7h0WvXiLqGcMRtSWVEuTV0dLMJp/Y5OSdD/HkZxSQEK+aO01h63/4SliBFN0BR4Ib 6F8dl2YAw== X-HalOne-ID: 428b86cc-1a8d-11ee-8bd0-b90637070a9d Received: from ravnborg.org (2-105-2-98-cable.dk.customer.tdc.net [2.105.2.98]) by mailrelay3 (Halon) with ESMTPSA id 428b86cc-1a8d-11ee-8bd0-b90637070a9d; Tue, 04 Jul 2023 17:07:32 +0000 (UTC) Date: Tue, 4 Jul 2023 19:07:31 +0200 From: Sam Ravnborg To: Daniel Thompson Cc: Mans Rullgard , linux-fbdev@vger.kernel.org, Jingoo Han , Helge Deller , Lee Jones , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Tomi Valkeinen Subject: Re: [PATCH] backlight: led_bl: fix initial power state Message-ID: <20230704170731.GB940443@ravnborg.org> References: <20230704140750.25799-1-mans@mansr.com> <20230704150310.GA385243@aspen.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230704150310.GA385243@aspen.lan> Precedence: bulk List-ID: X-Mailing-List: linux-fbdev@vger.kernel.org Hi Daniel, > > @@ -200,8 +200,8 @@ static int led_bl_probe(struct platform_device *pdev) > > props.type = BACKLIGHT_RAW; > > props.max_brightness = priv->max_brightness; > > props.brightness = priv->default_brightness; > > - props.power = (priv->default_brightness > 0) ? FB_BLANK_POWERDOWN : > > - FB_BLANK_UNBLANK; > > + props.power = (priv->default_brightness > 0) ? FB_BLANK_UNBLANK : > > + FB_BLANK_POWERDOWN; > > The logic was wrong before but I think will still be wrong after the > change too (e.g. the bogus logic is probably avoiding backlight flicker > in some use cases). > > The logic here needs to be similar to what pwm_bl.c implements in > pwm_backlight_initial_power_state(). Whilst it might be better > to implement this in led_bl_get_leds() let me show what I mean > in code that fits in the current line: > > /* > * Activate the backlight if the LEDs are already lit *or* > * there is no phandle link (meaning the backlight power > * state cannot be synced with the display state). > */ > props.power = (active_at_boot || !dev->node->phandle) ? > FB_BLANK_UNBLANK : FB_BLANK_POWERDOWN; > The following code does the same using helpers: if (active_at_boot || !dev->node->phandle)) backlight_enable(bd); else backlight_disable(bd); The code needs to execute after backlight_device_register() so maybe not so great an idea?!? Sam