| Message ID | 20230726080001.337353-3-tamnguyenchi@os.amperecomputing.com |
|---|---|
| State | New |
| Headers | show |
| Series | i2c: designware: Handle invalid SMBus block data response length value | expand |
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>
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. > > 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> Applied to for-current, thanks!
diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c index e96276d1b002..c51fc1f4b97e 100644 --- a/drivers/i2c/busses/i2c-designware-master.c +++ b/drivers/i2c/busses/i2c-designware-master.c @@ -528,8 +528,19 @@ i2c_dw_read(struct dw_i2c_dev *dev) regmap_read(dev->map, DW_IC_DATA_CMD, &tmp); tmp &= DW_IC_DATA_CMD_DAT; /* Ensure length byte is a valid value */ - if (flags & I2C_M_RECV_LEN && - tmp <= I2C_SMBUS_BLOCK_MAX && tmp > 0) { + if (flags & I2C_M_RECV_LEN) { + /* + * if IC_EMPTYFIFO_HOLD_MASTER_EN is set, which cannot be + * detected from the registers, the controller can be + * disabled if the STOP bit is set. But it is only set + * after receiving block data response length in + * I2C_FUNC_SMBUS_BLOCK_DATA case. That needs to read + * another byte with STOP bit set when the block data + * response length is invalid to complete the transaction. + */ + if (!tmp || tmp > I2C_SMBUS_BLOCK_MAX) + tmp = 1; + len = i2c_dw_recv_len(dev, tmp); } *buf++ = tmp;
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(-)