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 7DA3D218EB1; Mon, 27 Oct 2025 18:39:56 +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=1761590396; cv=none; b=LtXQ/Rpn7tpQyVvZBjix3BEZ56CpL/ky49Eqs9MCqEGjCSBxrzjbuXovzx8HCBNvuEyqmR+u9M78ShUapWu7oIXK5gdpPQwb3iKpwdSjpw4d5jSVh9mCMmFR+Is7BZyWPM6ns03mrYHE524iJ2RpSBuJVkuc3aaY32oOYb7/KjA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761590396; c=relaxed/simple; bh=cSkJ8ddCQZVc02kK4DTBkAeMUxPSaYCqEtuuoCbAIQU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=WWTRz0j8hbT/fzVrWN7HTr4RDSddq4zIJwVij+W5YAVjsgkTHtn6yBqsfwOiVcrBkTa7SzNcwevsW/JXXkpCcOyDNO0sNQPEcsZF7djM5XAbU0oqHq8pIsDEx7kNJy8EK1VvE77aja3t46iuEsWpj72ZMyIbggVq5eHsOejrYuo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=RK8JX9kN; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="RK8JX9kN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 12B29C113D0; Mon, 27 Oct 2025 18:39:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1761590396; bh=cSkJ8ddCQZVc02kK4DTBkAeMUxPSaYCqEtuuoCbAIQU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RK8JX9kNtxbDb7ZoyxmUmoDkXsyKXtuKdWoHOVNO+yfPH+kJUPvbloRLaJ0FKp1gH HsNsJ/c47w6uX+cIqbwIUke1dsWAQ1xBmEg8GIvzyFTpWk5NrWkvh+OSx1B7BulziO Nd8wAKgZhqM0HbrOKTDtOU8Jr1+eF4P0KXEJ1XPM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, "Leilk.Liu" , Chen-Yu Tsai , Wolfram Sang , Sasha Levin Subject: [PATCH 5.4 029/224] i2c: mediatek: fix potential incorrect use of I2C_MASTER_WRRD Date: Mon, 27 Oct 2025 19:32:55 +0100 Message-ID: <20251027183509.786297134@linuxfoundation.org> X-Mailer: git-send-email 2.51.1 In-Reply-To: <20251027183508.963233542@linuxfoundation.org> References: <20251027183508.963233542@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 5.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Leilk.Liu [ Upstream commit b492183652808e0f389272bf63dc836241b287ff ] The old IC does not support the I2C_MASTER_WRRD (write-then-read) function, but the current code’s handling of i2c->auto_restart may potentially lead to entering the I2C_MASTER_WRRD software flow, resulting in unexpected bugs. Instead of repurposing the auto_restart flag, add a separate flag to signal I2C_MASTER_WRRD operations. Also fix handling of msgs. If the operation (i2c->op) is I2C_MASTER_WRRD, then the msgs pointer is incremented by 2. For all other operations, msgs is simply incremented by 1. Fixes: b2ed11e224a2 ("I2C: mediatek: Add driver for MediaTek MT8173 I2C controller") Signed-off-by: Leilk.Liu Suggested-by: Chen-Yu Tsai Reviewed-by: Chen-Yu Tsai Signed-off-by: Wolfram Sang Signed-off-by: Sasha Levin --- drivers/i2c/busses/i2c-mt65xx.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) diff --git a/drivers/i2c/busses/i2c-mt65xx.c b/drivers/i2c/busses/i2c-mt65xx.c index 5587e7c549c4f..2b56ad08efed1 100644 --- a/drivers/i2c/busses/i2c-mt65xx.c +++ b/drivers/i2c/busses/i2c-mt65xx.c @@ -782,6 +782,7 @@ static int mtk_i2c_transfer(struct i2c_adapter *adap, { int ret; int left_num = num; + bool write_then_read_en = false; struct mtk_i2c *i2c = i2c_get_adapdata(adap); ret = mtk_i2c_clock_enable(i2c); @@ -795,6 +796,7 @@ static int mtk_i2c_transfer(struct i2c_adapter *adap, if (!(msgs[0].flags & I2C_M_RD) && (msgs[1].flags & I2C_M_RD) && msgs[0].addr == msgs[1].addr) { i2c->auto_restart = 0; + write_then_read_en = true; } } @@ -818,12 +820,10 @@ static int mtk_i2c_transfer(struct i2c_adapter *adap, else i2c->op = I2C_MASTER_WR; - if (!i2c->auto_restart) { - if (num > 1) { - /* combined two messages into one transaction */ - i2c->op = I2C_MASTER_WRRD; - left_num--; - } + if (write_then_read_en) { + /* combined two messages into one transaction */ + i2c->op = I2C_MASTER_WRRD; + left_num--; } /* always use DMA mode. */ @@ -831,7 +831,10 @@ static int mtk_i2c_transfer(struct i2c_adapter *adap, if (ret < 0) goto err_exit; - msgs++; + if (i2c->op == I2C_MASTER_WRRD) + msgs += 2; + else + msgs++; } /* the return value is number of executed messages */ ret = num; -- 2.51.0