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i2c: bcm2835: Can't support I2C_M_IGNORE_NAK

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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>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
Noralf Trønnes 2016-10-03 22:06:11 +02:00 committed by Wolfram Sang
parent 23c9540b3a
commit 8d2cc5cc6e
1 changed files with 0 additions and 4 deletions
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4
drivers/i2c/busses/i2c-bcm2835.c
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@ -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)