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 0A2AC32E13D; Mon, 17 Nov 2025 12:39:48 +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=1763383192; cv=none; b=VqDvCucdp9ncwy4GE/Uy2U+bS8CqqlPZ2UV2BbbB4TCbKQ6Y3xzKqYVOP49awQzCgm4Zw3AiUTBQvbLuz2Fuz56zgu9XbXnIRt9ynJXNidAdYUvpH3ZzJKHFJAk8bbTz8UV49+kmDTrSPLRxFv14dWfsmQ7D6CUU+9ePvUm1jlg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763383192; c=relaxed/simple; bh=Jw2sRzJoJU/CuzcziJhRnNu6CtWaCgLJpIwQLt9l66s=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=R26Y942rBejQnYDeq+/4mB9EWMEXpoIF1YgnW753KGYG+RYNqkBRApTJcooiIVlFELhrxOzZ4MtZ6XjFtxNvzWccjv1CrEcUuKYYdJfPA7Susb3Pzhglyq50Nq8cgt+/4K7NdhBXo+Zb38KSNj3il2IUWzWYRbgT+HC1q7jcMeE= 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=mUMAUTy7; 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="mUMAUTy7" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1763383187; bh=Jw2sRzJoJU/CuzcziJhRnNu6CtWaCgLJpIwQLt9l66s=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=mUMAUTy7PNxVnPK272ufjc6P2C/ZiAcQF/azJRUjLl9QAQIiI73jDd7pS8u/SjerD 6o3iqGxrSEaskBwr/i8yLVTJ25fZlTktErORF5bIetaOWLnXRAWTSR0hsRowW0K3JW mFZf3RO597TFbLvgzs9EXtqZQJEZkHusiGMgVwJAbFtWPZL/CJPPkarclyQyj8eaih CxdtNncPX7f7GXCX4XDeWOjpPTka+9eI9sS+WURVkLW18EJNWHJSrFQ90q050lR14F P9am3tZMqe3VQprE/X08Efb5rdmtvSnKyJl2sItlzAS9tSok69HCYDdV0hVOxO7Wwp NUlo6OXHvmXUg== Received: from [192.168.1.100] (2-237-20-237.ip236.fastwebnet.it [2.237.20.237]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (No client certificate requested) (Authenticated sender: kholk11) by bali.collaboradmins.com (Postfix) with ESMTPSA id 7C17317E0B85; Mon, 17 Nov 2025 13:39:46 +0100 (CET) Message-ID: Date: Mon, 17 Nov 2025 13:39:46 +0100 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 13/13] interconnect: mediatek: Aggregate bandwidth with saturating add To: Nicolas Frattaroli , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Matthias Brugger , Henry Chen , Georgi Djakov Cc: kernel@collabora.com, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, linux-pm@vger.kernel.org References: <20251114-mt8196-dvfsrc-v1-0-b956d4631468@collabora.com> <20251114-mt8196-dvfsrc-v1-13-b956d4631468@collabora.com> From: AngeloGioacchino Del Regno Content-Language: en-US In-Reply-To: <20251114-mt8196-dvfsrc-v1-13-b956d4631468@collabora.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Il 14/11/25 17:54, Nicolas Frattaroli ha scritto: > By using a regular non-overflow-checking add, the MediaTek icc-emi > driver will happy wrap at U32_MAX + 1 to 0. As it's common for the > interconnect core to fill in INT_MAX values, this is not a hypothetical > situation, but something that actually happens in regular use. This > would be pretty disasterous if anything used this driver. > > Replace the addition with an overflow-checked addition from overflow.h, > and saturate to U32_MAX if an overflow is detected. > > Fixes: b45293799f75 ("interconnect: mediatek: Add MediaTek MT8183/8195 EMI Interconnect driver") > Signed-off-by: Nicolas Frattaroli Reviewed-by: AngeloGioacchino Del Regno