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Date:   Mon, 14 Aug 2023 15:29:40 +0200
From:   Wolfram Sang <wsa@kernel.org>
To:     Tam Nguyen <tamnguyenchi@os.amperecomputing.com>
Cc:     linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org,
        patches@amperecomputing.com, jarkko.nikula@linux.intel.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
Subject: Re: [PATCH v2 2/2] i2c: designware: Handle invalid SMBus block data
 response length value
Message-ID: <ZNosRDSWSa4Pbs37@shikoro>
Mail-Followup-To: Wolfram Sang <wsa@kernel.org>,
        Tam Nguyen <tamnguyenchi@os.amperecomputing.com>,
        linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org,
        patches@amperecomputing.com, jarkko.nikula@linux.intel.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>
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On Wed, Jul 26, 2023 at 03:00:01PM +0700, 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.
>=20
> In case IC_EMPTYFIFO_HOLD_MASTER_EN=3D=3D1, 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.
>=20
> Avoid this by issuing another dump read to reach the stop condition when
> an invalid length byte is received.
>=20
> Cc: stable@vger.kernel.org
> Signed-off-by: Tam Nguyen <tamnguyenchi@os.amperecomputing.com>

Applied to for-current, thanks!


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