[PATCH v2 4/8] i2c: bcm2835: Can't support I2C_M_IGNORE_NAK

From: Noralf TrÃnnes
Date: Tue Sep 27 2016 - 08:00:14 EST

The controller can't support this flag, so remove it.

Documentation/i2c/i2c-protocol states that all of the message is sent:

Normally message is interrupted immediately if there is [NA] from the
client. Setting this flag treats any [NA] as [A], and all of
message is sent.

>From the BCM2835 ARM Peripherals datasheet:

The ERR field is set when the slave fails to acknowledge either
its address or a data byte written to it.

So when the controller doesn't receive an ack, it sets ERR and raises
an interrupt. In other words, the whole message is not sent.

Signed-off-by: Noralf TrÃnnes <noralf@xxxxxxxxxxx>
drivers/i2c/busses/i2c-bcm2835.c | 4 ----
1 file changed, 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-bcm2835.c b/drivers/i2c/busses/i2c-bcm2835.c
index 370a322..4e08add 100644
--- a/drivers/i2c/busses/i2c-bcm2835.c
+++ b/drivers/i2c/busses/i2c-bcm2835.c
@@ -203,10 +203,6 @@ static int bcm2835_i2c_xfer_msg(struct bcm2835_i2c_dev *i2c_dev,
if (likely(!i2c_dev->msg_err))
return 0;

- if ((i2c_dev->msg_err & BCM2835_I2C_S_ERR) &&
- (msg->flags & I2C_M_IGNORE_NAK))
- return 0;
dev_err_ratelimited(i2c_dev->dev, "i2c transfer failed: %x\n",