brcm2708: rename all patches from raspberrypi git tree to use 950 prefix

[openwrt/staging/chunkeey.git] / target / linux / brcm2708 / patches-4.9 / 950-0109-i2c-bcm2835-Can-t-support-I2C_M_IGNORE_NAK.patch

diff --git a/target/linux/brcm2708/patches-4.9/950-0109-i2c-bcm2835-Can-t-support-I2C_M_IGNORE_NAK.patch b/target/linux/brcm2708/patches-4.9/950-0109-i2c-bcm2835-Can-t-support-I2C_M_IGNORE_NAK.patch
new file mode 100644 (file)
index 0000000..a913c50
--- /dev/null
+++ b/target/linux/brcm2708/patches-4.9/950-0109-i2c-bcm2835-Can-t-support-I2C_M_IGNORE_NAK.patch
@@ -0,0 +1,44 @@
+From 40c63177d4c0f4755a148503c3b8bb2192ce8c0e Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Noralf=20Tr=C3=B8nnes?= <noralf@tronnes.org>
+Date: Thu, 22 Sep 2016 22:05:50 +0200
+Subject: [PATCH] i2c: bcm2835: Can't support I2C_M_IGNORE_NAK
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+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(-)
+
+--- 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 b
+       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)