From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bali.collaboradmins.com (bali.collaboradmins.com [148.251.105.195]) (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 AA4983976A0; Tue, 8 Sep 2026 07:14:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.251.105.195 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788851699; cv=none; b=QAlo0dETmCLab8AWe7N9V5mNxJwse2dNllKpyi6UsXPeT8eZS3Z4TWpno1t62/LovWDIs8TrvSlInzs5AW6+LzgUEeebwXQV7Gf182TbLl7YnarbIi5lVbKN4EquFZdeyvnivy9VzB95PbAG8ufULOxqr8NkLvHghY2NSri21Zs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788851699; c=relaxed/simple; bh=ArJeW2flTkb9rm1gkhAoy7DoxwAb/3A+bJJPz0B1eno=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=aoVjnRnvYWbSB4I/UXlff7kSZDtjL1Dd+ag+SG8UJ9hc+l+F72R9a/AeJL+XllconwsWhekMRZjpyRx9sjXNMgLRVOKwuN0UwqSgpSDQCOLqbriodXR0DOKOqSRj+33ZcBz8153nzzWfHYQepb+vhsu+0vHeZG/h3CYZVAAAwhQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com; spf=pass smtp.mailfrom=collabora.com; dkim=pass (2048-bit key) header.d=collabora.com header.i=@collabora.com header.b=LuGOZcyy; arc=none smtp.client-ip=148.251.105.195 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=collabora.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=collabora.com header.i=@collabora.com header.b="LuGOZcyy" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1788851695; bh=ArJeW2flTkb9rm1gkhAoy7DoxwAb/3A+bJJPz0B1eno=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=LuGOZcyyYxieMA3pMCJAyaJj4o8p1ih3RqpJ1LuoGQp+cy3nnBLkjNQS1Io4bo2wR 7628PQg3TYOICpTlTHfBOaYB1w8fXqkGR5OaZrC5DzS8+QmRSFAGrZ4AaDazBnz/MH yDfEtCZQXdrz7V/e0cizk0yfoL74Lzjxm18VJ5nHQHyv4nWuXOHTTOLYgJQZte062R TcaPBywqYnWCcqhCmBTW+72QziGLgPLBUGvFHAuUDVGp9WMlTMcBQakjgxUoxpO/Cc LhaB0TPUUMpAzxPVPOLMXYnkHH0RIbtOefVzc3cwxjswOHnUvmhBz+lyhE1iEtR0uI 9P0fTU1CLhe8w== Received: from [100.64.1.21] (unknown [100.64.1.21]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange x25519) (No client certificate requested) (Authenticated sender: kholk11) by bali.collaboradmins.com (Postfix) with ESMTPSA id 5070217E027D; Tue, 08 Sep 2026 09:14:55 +0200 (CEST) Message-ID: <30806e9c-8d37-4f99-b9d6-a2819acaeb50@collabora.com> Date: Tue, 8 Sep 2026 09:14:54 +0200 Precedence: bulk X-Mailing-List: linux-pwm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] pwm: mtk-disp: Fix period readback To: Chen-Yu Tsai , =?UTF-8?Q?Uwe_Kleine-K=C3=B6nig?= , Matthias Brugger Cc: linux-pwm@vger.kernel.org, linux-mediatek@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Jitao Shi References: <20260827105738.8570-1-wenst@chromium.org> From: AngeloGioacchino Del Regno Content-Language: en-US In-Reply-To: <20260827105738.8570-1-wenst@chromium.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 8/27/26 12:57, Chen-Yu Tsai wrote: > The period value stored in the register is the number of clock cycles - 1. > > Account for the offset when calculating the period in nanoseconds. This > fixes the discrepancy reported by the pwm core when CONFIG_PWM_DEBUG=1: > > mediatek-disp-pwm 1100e000.pwm: .apply is not idempotent > (ena=1 pol=0 281500/499875) -> (ena=1 pol=0 281500/499750) > > Calculation discrepancy in the driver was found by AI run by a colleague > while debugging another PWM related issue. Check against SoC datasheet > and fix done by the author. > > Fixes: 3f2b16734914 ("pwm: mtk-disp: Implement atomic API .get_state()") > Cc: Jitao Shi > Signed-off-by: Chen-Yu Tsai Reviewed-by: AngeloGioacchino Del Regno