[lkml]   [2012]   [May]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
Patch in this message
Subject[PATCH 1/8] i2c: i2c-bfin-twi: Illegal i2c bus lock upon certain transfer scenarios.
From: Michael Hennerich <>

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 <>

git-svn-id: svn://localhost/svn/linux-kernel/trunk@9011 526b6c2d-f592-4532-a319-5dd88ccb003d
drivers/i2c/busses/i2c-bfin-twi.c | 4 ++++
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 cdb59e5..e6dd3c9 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,
} else if (iface->manual_stop) {
+ /* Avoid possible bus stall -
+ * Flush FIFO before issuing the STOP condition
+ */
+ read_RCV_DATA16(iface);
read_MASTER_CTL(iface) | STOP);
} else if (iface->cur_mode == TWI_I2C_MODE_REPEAT &&

 \ /
  Last update: 2012-05-16 10:21    [from the cache]
©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site