Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1492799 > unrolled thread

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

Back to article view | Back to linux.kernel

This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by below is the oldest one visible, not the original post.

Contents

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

#1492799 — [PATCH v3 4/7] i2c: bcm2835: Can't support I2C_M_IGNORE_NAK

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

[toc] | [standalone]

Back to top | Article view | linux.kernel

csiph-web