[v2,for-4.9,08/32] i2c: bcm2835: Can't support I2C_M_IGNORE_NAK

Message ID 1491388344-13521-9-git-send-email-amit.pundir@linaro.org
State New
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Series
  • Stable commits picked up from lede project
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Commit Message

Amit Pundir April 5, 2017, 10:32 a.m.
From: Noralf Trønnes <noralf@tronnes.org>


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>

(cherry picked from commit 8d2cc5cc6ee5c0fc48a96bb29af55fc700f66fdf)
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>

---
 drivers/i2c/busses/i2c-bcm2835.c | 4 ----
 1 file changed, 4 deletions(-)

-- 
2.7.4

Patch

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)