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Subject[PATCH 1/8] i2c: i2c-bfin-twi: Illegal i2c bus lock upon certain transfer scenarios.
Date
From: Michael Hennerich <michael.hennerich@analog.com>

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>

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,
iface->transPtr++;
iface->readNum--;
} else if (iface->manual_stop) {
+ /* 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 &&
--
1.7.0.4



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