Messages in this thread Patch in this message |  | | From | Noralf Trønnes <> | Subject | [PATCH v4 4/7] i2c: bcm2835: Can't support I2C_M_IGNORE_NAK | Date | Mon, 3 Oct 2016 22:06:11 +0200 |
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The controller can't support this flag, so remove it.
Documentation/i2c/i2c-protocol states that all of the message is sent:
I2C_M_IGNORE_NAK: 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 Trønnes <noralf@tronnes.org> Reviewed-by: Eric Anholt <eric@anholt.net> --- 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 54d510a..565ef69 100644 --- a/drivers/i2c/busses/i2c-bcm2835.c +++ b/drivers/i2c/busses/i2c-bcm2835.c @@ -212,10 +212,6 @@ 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_dbg(i2c_dev->dev, "i2c transfer failed: %x\n", i2c_dev->msg_err); if (i2c_dev->msg_err & BCM2835_I2C_S_ERR) -- 2.8.2
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