From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 96CEE2F50; Sun, 20 Jul 2025 12:49:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753015792; cv=none; b=UcebZgLyA0Ff7VWP0JqRJMfI1nNFFFu1lR1oDgtiLxjQp60ssxuNHg4RY95J7+Ch8bSk8BKQJLm4UMJD2jCxEvgrxvv4okDN7f+LIZBGcMWTv4jF/By+30KGdKnViVsWzvAg3s/4NjvSRUGsyvvES22MiuOOI8ew6CHooRSgddM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753015792; c=relaxed/simple; bh=oxFpdknoeX5Vw+UUVKkbtToVxydEtk2SgKvQHO4LClA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=FgHcLw7L0lzeJeakZehX1J1GdO74neqbSP+a7+oN9kAOpC0SS1uzqODo/+hK8X/zcSxYf2e0OFtgaQw6Db2Xb4TK8VntKslwFV3GXlu4L1SArK+5I3fig8KluHVYeENo8zLFEdcf9pvkaFB/W65S7PDCj29EMK4knm+OfmOApNE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GvzWUlFD; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="GvzWUlFD" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 66B65C4CEE7; Sun, 20 Jul 2025 12:49:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1753015792; bh=oxFpdknoeX5Vw+UUVKkbtToVxydEtk2SgKvQHO4LClA=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=GvzWUlFD5xtVgR4UOIIYcFPe2ZprorZ8ZGG+bXlshclLbKYjwp40Eg+C4sLajjrPF 62cjZW0idnISxvQ1FVr8yi5SwGi8whd368XgEGRjERcAJpoda4/InBqp++bc+oiprP TUNIg4pzl2ymi4ELcsDptVd4Qwx6Qpx/8y4lzwxVqXpYBvKflp6UGoLqw/09r8NjF0 3hrHJuRsZeCpJZKlMcDFamJD0HAcI5gPUdV77NNlGOJqhZ5U2QK0DVfUPBftiZCNz8 +Bi7NqFynEo+emRFifeUKiBT7xs+qy0IzOV6Ey5Ktu/yVMF+342ZWb4fjfua438tja g7AqvYW8liYCw== Message-ID: <18a71fc3-dd01-4335-9655-716c87048530@kernel.org> Date: Sun, 20 Jul 2025 07:49:50 -0500 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [REGRESSION] [PATCH] drm/amd/display: fix initial backlight brightness calculation To: Lauri Tirkkonen Cc: stable@vger.kernel.org, regressions@lists.linux.dev, amd-gfx@lists.freedesktop.org, Wayne Lin , Alex Deucher , Greg Kroah-Hartman References: <46de4f2a-8836-42cd-a621-ae3e782bf253@kernel.org> <664c5661-0fa8-41db-b55d-7f1f58e40142@kernel.org> Content-Language: en-US From: Mario Limonciello In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 7/20/25 4:36 AM, Lauri Tirkkonen wrote: > DIV_ROUND_CLOSEST(x, 100) returns either 0 or 1 if 0 division needs to be performed after the multiplication and not the > other way around, to properly scale the value. > > Fixes: 6c56c8ec6f97 ("drm/amd/display: Fix default DC and AC levels") > Signed-off-by: Lauri Tirkkonen > --- > drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > index f58fa5da7fe5..8a5b5dfad1ab 100644 > --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c > @@ -4941,9 +4941,9 @@ amdgpu_dm_register_backlight_device(struct amdgpu_dm_connector *aconnector) > caps = &dm->backlight_caps[aconnector->bl_idx]; > if (get_brightness_range(caps, &min, &max)) { > if (power_supply_is_system_supplied() > 0) > - props.brightness = (max - min) * DIV_ROUND_CLOSEST(caps->ac_level, 100); > + props.brightness = DIV_ROUND_CLOSEST((max - min) * caps->ac_level, 100); > else > - props.brightness = (max - min) * DIV_ROUND_CLOSEST(caps->dc_level, 100); > + props.brightness = DIV_ROUND_CLOSEST((max - min) * caps->dc_level, 100); > /* min is zero, so max needs to be adjusted */ > props.max_brightness = max - min; > drm_dbg(drm, "Backlight caps: min: %d, max: %d, ac %d, dc %d\n", min, max, Thanks! The change makes sense. Besides Greg's comments can you please send out of the regression thread? IMO This should be it's own patch thread.