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 7A798C001B0 for ; Tue, 4 Jul 2023 15:40:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230197AbjGDPk5 (ORCPT ); Tue, 4 Jul 2023 11:40:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49976 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230156AbjGDPk4 (ORCPT ); Tue, 4 Jul 2023 11:40:56 -0400 Received: from mail-wm1-x329.google.com (mail-wm1-x329.google.com [IPv6:2a00:1450:4864:20::329]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CD9781B2 for ; Tue, 4 Jul 2023 08:40:54 -0700 (PDT) Received: by mail-wm1-x329.google.com with SMTP id 5b1f17b1804b1-3fbc5d5742bso57406345e9.2 for ; Tue, 04 Jul 2023 08:40:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1688485253; x=1691077253; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date:from:to :cc:subject:date:message-id:reply-to; bh=dETgL6aN2zUTbUFg9iSwg8ejNwrd0bWe6o9LAE1dT5I=; b=J2qE6//r39TaBSH1KbiE1TIqH0WGur8hFgV+NsAXGceRzRytpyUoQEnWPq7O7iM2i5 XCezzp9pWxTI2EvHkCTGwaTg6AidfN9Ig54m2M/KUNFSzOt2APlJ0CVFyfSiKC5uQBIY O2Hr95lpg8ZWt7ErOZLe34Zt59EpDyCP3Bl+4xYBjNw3bc2mGqRA5PaGI1HhQYIez9Ql wU2QA2cRvxKlc5I5mvPOTJpnKIxmAS6uLZ8P7RRULyNpRlaCQ8CqRsewlDFn1DwutleX PCqgvF97jifPV6zaDvZFDRdKy7eAJLlNCcSOnNoy/t4bvplC9uVR7eYtjF7l+dFgTJpX gHcA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1688485253; x=1691077253; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=dETgL6aN2zUTbUFg9iSwg8ejNwrd0bWe6o9LAE1dT5I=; b=Tiunn/NQ/+LjmZCce9gciD+r7pfCR7sJuX6W2nyVoWgoj+Qcdsju3XCtModa/GOXXp NbvmRFDH0mK27OlsXea+INNwdmRInmON8macJ9BNIIyu4Ll8ERNasdro2iKCL5V0e9+p Hr3nxoJJEj9XPbOhFNB6DM6yxCGnyEzauk+bnHQj/HkIAJshxvwHDobYCZo4F0npfrFB EHyR7CrykzQslA/JqHodaE54hMoUf8ex+bxFTkCo8OA2yMjfNmtqsthB6RLFK8jlgJN4 L8FDPhX6CErCpLX9Z5FgkisZyxLVoDJBjgHg9g0ujG1jg6sD2bRwGg8CKm7yLkYwDdei C7SQ== X-Gm-Message-State: AC+VfDxt1q+JIbWdo6qhI/0GUYMmxwNvKXpjG5Kf6CY3h9pYvPdCDyr2 jtWHqOPYZb/z8mW/xLwgFebb1g== X-Google-Smtp-Source: ACHHUZ5/+GjNc3y08OaN0unpphSTEbHVkt9PK6i+z80YL2bJvVkOutHzeXGXyxPs5woWSj5oQdQKug== X-Received: by 2002:a1c:7c05:0:b0:3f6:2ae:230e with SMTP id x5-20020a1c7c05000000b003f602ae230emr11643583wmc.3.1688485253234; Tue, 04 Jul 2023 08:40:53 -0700 (PDT) Received: from aspen.lan (aztw-34-b2-v4wan-166919-cust780.vm26.cable.virginm.net. [82.37.195.13]) by smtp.gmail.com with ESMTPSA id f10-20020a7bcd0a000000b003fa99969e61sm24767384wmj.45.2023.07.04.08.40.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 04 Jul 2023 08:40:52 -0700 (PDT) Date: Tue, 4 Jul 2023 16:40:51 +0100 From: Daniel Thompson To: =?iso-8859-1?Q?M=E5ns_Rullg=E5rd?= Cc: Lee Jones , Jingoo Han , Helge Deller , dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] backlight: led_bl: fix initial power state Message-ID: <20230704154051.GC385243@aspen.lan> References: <20230704140750.25799-1-mans@mansr.com> <20230704150310.GA385243@aspen.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-fbdev@vger.kernel.org On Tue, Jul 04, 2023 at 04:31:51PM +0100, Måns Rullgård wrote: > Daniel Thompson writes: > > > On Tue, Jul 04, 2023 at 03:07:50PM +0100, Mans Rullgard wrote: > >> The condition for the initial power state based on the default > >> brightness value is reversed. Fix it. > >> > >> Fixes: ae232e45acf9 ("backlight: add led-backlight driver") > >> Signed-off-by: Mans Rullgard > >> --- > >> drivers/video/backlight/led_bl.c | 4 ++-- > >> 1 file changed, 2 insertions(+), 2 deletions(-) > >> > >> diff --git a/drivers/video/backlight/led_bl.c b/drivers/video/backlight/led_bl.c > >> index 3259292fda76..28e83618a296 100644 > >> --- a/drivers/video/backlight/led_bl.c > >> +++ b/drivers/video/backlight/led_bl.c > >> @@ -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; > > > > Note that active_at_boot is not the same as (priv->default_brightness > 0) > > since the value read by led_bl_get_leds() can be clobbered when we > > parse the properties. > > Am I understanding correctly that the code should be using the > default_brightness value as set by led_bl_get_leds() to determine the > initial power state, not whatever default value the devicetree provides? Yes. The devicetree allows us to specify a default brightness but the DT value cannot not be used to decide if the backlight has already been lit up. Daniel.