Commit c39e8e43 authored Apr 22, 2013 by Steven A. Falco Committed by Wolfram Sang Apr 23, 2013

i2c: xiic: must always write 16-bit words to TX_FIFO



The TX_FIFO register is 10 bits wide.  The lower 8 bits are the data to be
written, while the upper two bits are flags to indicate stop/start.

The driver apparently attempted to optimize write access, by only writing a
byte in those cases where the stop/start bits are zero.  However, we have
seen cases where the lower byte is duplicated onto the upper byte by the
hardware, which causes inadvertent stop/starts.

This patch changes the write access to the transmit FIFO to always be 16 bits
wide.

Signed off by: Steven A. Falco <sfalco@harris.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Cc: stable@kernel.org

parent 73f37dc3

drivers/i2c/busses/i2c-xiic.c

+2 −4

Original line number	Diff line number	Diff line
		@@ -312,10 +312,8 @@ static void xiic_fill_tx_fifo(struct xiic_i2c *i2c)
		/* last message in transfer -> STOP */
		data \|= XIIC_TX_DYN_STOP_MASK;
		dev_dbg(i2c->adap.dev.parent, "%s TX STOP\n", __func__);

		}
		xiic_setreg16(i2c, XIIC_DTR_REG_OFFSET, data);
		} else
		xiic_setreg8(i2c, XIIC_DTR_REG_OFFSET, data);
		}
		}