From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 D96D336EA84 for ; Mon, 27 Jul 2026 12:19:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785154783; cv=none; b=imcQowz606PoJ22comozOpVKdLlSh6tS0os88h3xZ/j78hia6+KAc6GXZuUdeQxqT54YHB0UoCu6BZ2lFoGVe/l7cRmkroOSpRhOkDPJT9QsgWO9h4KTjVm7iUZpzY+GmJq6yTsH0hN02gDQwfl25W27cfIQCJ/bMwjCoAql5hA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785154783; c=relaxed/simple; bh=Ho+S3ya23lGBjFjGZfhGSyHvIHke/5zNkBZ6i9iow14=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ifU/XwmkU+cg3T8o8DdcIm/ZS4x+0DADYM1bih27WmbIUAudLXjG2qwX/aed5BKJLOohlUY/zDY9TTU3pSWm1LnZpXWxvuLohXOZijGtzfT/5FKFP9i2p3+wpBq54Z7/iufF82qCA2RK1Tv1fQu3dqkJmsHCt5HahJYTSyOV1Vk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=TdBPHZUs; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="TdBPHZUs" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E03A21F00A3A; Mon, 27 Jul 2026 12:19:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785154781; bh=0i/gKWW7Bvuj4OsZHaY6wqNvRaVzqz/naijwPh00tPg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=TdBPHZUs43J7KpZe72fPKtWWOvz9pnVUWuhiXAotr9B12Zk3K4JJ7/PiqsS6U58J9 eTLoWJcS5kfAChWK2PVzX2uwKzbbmPNtVmO2E8KHB6NSHHqTEAE8YC7vMXYTc+kQPn EhFXd4cetHDcTqrCIXVhqMOy99Lqqw131h+Rc2EQr0g1wVNpbRL81UlkF/LiaSmYV6 RZGrml09RMKFOJxy6dQX9hSrsedF7eAfpais+cCM4+511nhdAHsM7vJAEgQr3eKOQV cZ7BkxLMZ2mcLSb0jx1HT5i/BaUwBYOqNPnvBNxUb8y/Pb8+JOZFT0tRJl4oQzU79h A9okq+6fZkyUA== From: Sasha Levin To: stable@vger.kernel.org Cc: Vincent Jardin , Oleksij Rempel , Carlos Song , Stefan Eichenberger , Andi Shyti , Sasha Levin Subject: [PATCH 6.12.y 2/2] i2c: imx: fix locked bus on SMBus block-read of 0 (atomic) Date: Mon, 27 Jul 2026 08:19:38 -0400 Message-ID: <20260727121938.3777594-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260727121938.3777594-1-sashal@kernel.org> References: <2026072035-flight-slacker-b884@gregkh> <20260727121938.3777594-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Vincent Jardin [ Upstream commit cb2fc37857693b55909fb77dc2c87cfbc1cdc476 ] SMBus 3.1 6.5.7 allows a Block Read byte count of 0, but the atomic (polling) path rejects it as -EPROTO. Worse, it returns without a NACK+STOP: the next receive cycle has already started, so the target keeps holding SDA and the bus stays stuck until a power cycle for this i2c controller. Reading I2DR to obtain the count likewise arms the next byte on the count > I2C_SMBUS_BLOCK_MAX path, which also returned -EPROTO directly and left the bus held. Handle both: NACK the in-flight dummy byte (TXAK) and extend msgs->len so the existing last-byte handling emits STOP; the dummy byte is discarded. A count of 0 is a valid empty block read; a count above I2C_SMBUS_BLOCK_MAX is still reported as -EPROTO, but only after the bus has been released. The interrupt-driven path has the same flaw from a later commit and is fixed separately, as it carries a different Fixes: tag and stable range. Fixes: 8e8782c71595 ("i2c: imx: add SMBus block read support") Signed-off-by: Vincent Jardin Cc: # v3.16+ Acked-by: Oleksij Rempel Acked-by: Carlos Song Reviewed-by: Stefan Eichenberger Signed-off-by: Andi Shyti Link: https://lore.kernel.org/r/20260713-for-upstream-i2c-lx2160-fix-v1-v3-1-073ac9e103a5@free.fr Signed-off-by: Sasha Levin --- drivers/i2c/busses/i2c-imx.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c index 7c27d790a94882..45e71120fdc146 100644 --- a/drivers/i2c/busses/i2c-imx.c +++ b/drivers/i2c/busses/i2c-imx.c @@ -1180,6 +1180,7 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs, int i, result; unsigned int temp; int block_data = msgs->flags & I2C_M_RECV_LEN; + int block_err = 0; result = i2c_imx_prepare_read(i2c_imx, msgs, atomic, false); if (result) @@ -1201,8 +1202,20 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs, */ if ((!i) && block_data) { len = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR); - if ((len == 0) || (len > I2C_SMBUS_BLOCK_MAX)) - return -EPROTO; + if ((len == 0) || (len > I2C_SMBUS_BLOCK_MAX)) { + /* + * SMBus 3.1 6.5.7: support count byte of 0. + * I2C_SMBUS_BLOCK_MAX case should not hold the SDA either. + */ + if (len > I2C_SMBUS_BLOCK_MAX) + block_err = -EPROTO; + temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR); + temp |= I2CR_TXAK; + imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR); + msgs->buf[0] = 0; + msgs->len = 2; + continue; + } dev_dbg(&i2c_imx->adapter.dev, "<%s> read length: 0x%X\n", __func__, len); @@ -1250,7 +1263,7 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs, "<%s> read byte: B%d=0x%X\n", __func__, i, msgs->buf[i]); } - return 0; + return block_err; } static int i2c_imx_atomic_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs, -- 2.53.0