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authorMichael Hennerich <michael.hennerich@analog.com>2012-06-13 16:22:40 +0800
committerWolfram Sang <w.sang@pengutronix.de>2012-07-13 08:27:31 +0200
commit925594e03550f1825647ea5408a32bb9803d90f1 (patch)
treedebca96175b8e0a36a7265c71722887633fa873c /drivers/i2c
parentd61a9095155e832287552a9e565b8756ee293c46 (diff)
downloadtalos-op-linux-925594e03550f1825647ea5408a32bb9803d90f1.tar.gz
talos-op-linux-925594e03550f1825647ea5408a32bb9803d90f1.zip
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>
Diffstat (limited to 'drivers/i2c')
-rw-r--r--drivers/i2c/busses/i2c-bfin-twi.c4
1 files changed, 4 insertions, 0 deletions
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 &&
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