Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <d1ec82a2-5c16-c3dd-147f-1e5256acffcd@linux.intel.com>
Date:   Thu, 27 Jul 2023 13:49:36 +0300
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101
 Firefox/102.0 Thunderbird/102.13.0
Subject: Re: [PATCH v2 2/2] i2c: designware: Handle invalid SMBus block data
 response length value
Content-Language: en-US
To:     Tam Nguyen <tamnguyenchi@os.amperecomputing.com>,
        linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org
Cc:     patches@amperecomputing.com, andriy.shevchenko@linux.intel.com,
        mika.westerberg@linux.intel.com, jsd@semihalf.com,
        chuong@os.amperecomputing.com, darren@os.amperecomputing.com,
        stable@vger.kernel.org
References: <20230726080001.337353-1-tamnguyenchi@os.amperecomputing.com>
 <20230726080001.337353-3-tamnguyenchi@os.amperecomputing.com>
From:   Jarkko Nikula <jarkko.nikula@linux.intel.com>
In-Reply-To: <20230726080001.337353-3-tamnguyenchi@os.amperecomputing.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 7/26/23 11:00, Tam Nguyen wrote:
> In the I2C_FUNC_SMBUS_BLOCK_DATA case, the invalid length byte value
> (outside of 1-32) of the SMBus block data response from the Slave device
> is not correctly handled by the I2C Designware driver.
> 
> In case IC_EMPTYFIFO_HOLD_MASTER_EN==1, which cannot be detected
> from the registers, the Master can be disabled only if the STOP bit
> is set. Without STOP bit set, the Master remains active, holding the bus
> until receiving a block data response length. This hangs the bus and
> is unrecoverable.
> 
> Avoid this by issuing another dump read to reach the stop condition when
> an invalid length byte is received.
> 
> Cc: stable@vger.kernel.org
> Signed-off-by: Tam Nguyen <tamnguyenchi@os.amperecomputing.com>
> ---
>   drivers/i2c/busses/i2c-designware-master.c | 15 +++++++++++++--
>   1 file changed, 13 insertions(+), 2 deletions(-)
> 
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>