[PATCH v3 4/7] i2c: bcm2835: Can't support I2C_M_IGNORE_NAK

From	Noralf Trønnes <noralf@tronnes.org>
Newsgroups	linux.kernel
Subject	[PATCH v3 4/7] i2c: bcm2835: Can't support I2C_M_IGNORE_NAK
Date	2016-09-28 20:00 +0200
Message-ID	<smrjb-1pQ-1@gated-at.bofh.it> (permalink)
References	<smrjb-1pQ-3@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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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>
---
 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 8cdb139..99857f8 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_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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[PATCH v3 4/7] i2c: bcm2835: Can't support I2C_M_IGNORE_NAK Noralf Trønnes <noralf@tronnes.org> - 2016-09-28 20:00 +0200

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