| Message ID | 20200616154328.2866-1-sultan@kerneltoast.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] i2c: designware: Only check the first byte for SMBus block read length | expand |
On 6/16/20 6:43 PM, Sultan Alsawaf wrote: > From: Sultan Alsawaf <sultan@kerneltoast.com> > > SMBus block reads can be broken because the read function will just skip > over bytes it doesn't like until reaching a byte that conforms to the > length restrictions for block reads. This is problematic when it isn't > known if the incoming payload is indeed a conforming block read. > > According to the SMBus specification, block reads will only send the > payload length in the first byte, so we can fix this by only considering > the first byte in a sequence for block read length purposes. > > Fixes: c3ae106050b9 ("i2c: designware: Implement support for SMBus block read and write") > Signed-off-by: Sultan Alsawaf <sultan@kerneltoast.com> > --- > drivers/i2c/busses/i2c-designware-master.c | 16 +++++++--------- > 1 file changed, 7 insertions(+), 9 deletions(-) > Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c index d6425ad6e6a3..d22271438869 100644 --- a/drivers/i2c/busses/i2c-designware-master.c +++ b/drivers/i2c/busses/i2c-designware-master.c @@ -391,14 +391,10 @@ i2c_dw_recv_len(struct dw_i2c_dev *dev, u8 len) struct i2c_msg *msgs = dev->msgs; u32 flags = msgs[dev->msg_read_idx].flags; - /* - * Adjust the buffer length and mask the flag - * after receiving the first byte. - */ + /* Adjust the buffer length */ len += (flags & I2C_CLIENT_PEC) ? 2 : 1; dev->tx_buf_len = len - min_t(u8, len, dev->rx_outstanding); msgs[dev->msg_read_idx].len = len; - msgs[dev->msg_read_idx].flags &= ~I2C_M_RECV_LEN; return len; } @@ -430,10 +426,12 @@ i2c_dw_read(struct dw_i2c_dev *dev) u32 flags = msgs[dev->msg_read_idx].flags; regmap_read(dev->map, DW_IC_DATA_CMD, &tmp); - /* Ensure length byte is a valid value */ - if (flags & I2C_M_RECV_LEN && - tmp <= I2C_SMBUS_BLOCK_MAX && tmp > 0) { - len = i2c_dw_recv_len(dev, tmp); + if (flags & I2C_M_RECV_LEN) { + /* Ensure length byte is a valid value */ + if (tmp <= I2C_SMBUS_BLOCK_MAX && tmp > 0) + len = i2c_dw_recv_len(dev, tmp); + /* Mask the flag after receiving the first byte */ + msgs[dev->msg_read_idx].flags &= ~I2C_M_RECV_LEN; } *buf++ = tmp; dev->rx_outstanding--;