From: Michael Hennerich Date: Wed, 13 Jun 2012 08:22:40 +0000 (+0800) Subject: i2c: i2c-bfin-twi: Illegal i2c bus lock upon certain transfer scenarios. X-Git-Tag: firefly_0821_release~3680^2~2323^2~18 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=925594e03550f1825647ea5408a32bb9803d90f1;p=firefly-linux-kernel-4.4.55.git 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 Signed-off-by: Sonic Zhang Signed-off-by: Wolfram Sang --- diff --git a/drivers/i2c/busses/i2c-bfin-twi.c b/drivers/i2c/busses/i2c-bfin-twi.c index 515822429b19..c2e6b7849e8d 100644 --- a/drivers/i2c/busses/i2c-bfin-twi.c +++ b/drivers/i2c/busses/i2c-bfin-twi.c @@ -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 &&