Commit 925594e0 authored Jun 13, 2012 by Michael Hennerich Committed by Wolfram Sang Jul 13, 2012

i2c: i2c-bfin-twi: Illegal i2c bus lock upon certain transfer scenarios.



For transfer counts > 255 bytes i2c-bfin-twi sets the data
transfer counter DCNT to 0xFF indicating unlimited transfers.
It then uses a flag iface->manual_stop to manually issue the STOP
condition, once the required amount of bytes are received.

We found that on I2C receive operation issuing the STOP condition
together with a FULL RCV FIFO (2bytes) will cause SDA and SCL be
constantly driven low.

Temporary workaround until further investigation:
Discard the RCV FIFO before issuing the STOP condition.

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>

parent d61a9095

drivers/i2c/busses/i2c-bfin-twi.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -131,6 +131,10 @@ static void bfin_twi_handle_interrupt(struct bfin_twi_iface *iface,
		iface->transPtr++;
		iface->readNum--;
		} else if (iface->manual_stop) {
		/* Temporary workaround to avoid possible bus stall -
		* Flush FIFO before issuing the STOP condition
		*/
		read_RCV_DATA16(iface);
		write_MASTER_CTL(iface,
		read_MASTER_CTL(iface) \| STOP);
		} else if (iface->cur_mode == TWI_I2C_MODE_REPEAT &&

Admin message