imx6: add i2c retries for Ventana /dev/i2c-0

On Ventana boards the Gateworks System Controller is the only device on I2C1
(/dev/i2c-0) and it can NAK transfers if it is busy in an ADC loop. Because
this is a multi-function device with several slave addresses it is best to
add retries at the controller level instead of within each slave driver. This
adds a patch that adds 3 retries for i2c transactions only for Ventana boards
and only for I2C1

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Pushpal Sidhu <psidhu@gateworks.com>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@48012 3c298f89-4303-0410-b956-a3cf2f4a3e73

diff --git a/target/linux/imx6/patches-4.3/207-i2c-imx-add-retries-for-NAK-s-on-ventana-boards.patch b/target/linux/imx6/patches-4.3/207-i2c-imx-add-retries-for-NAK-s-on-ventana-boards.patch
new file mode 100644 (file)
index 0000000..bfb5707
--- /dev/null
+++ b/target/linux/imx6/patches-4.3/207-i2c-imx-add-retries-for-NAK-s-on-ventana-boards.patch
@@ -0,0 +1,24 @@
+Index: linux-4.3/drivers/i2c/busses/i2c-imx.c
+===================================================================
+--- linux-4.3.orig/drivers/i2c/busses/i2c-imx.c        2015-11-01 16:05:25.000000000 -0800
++++ linux-4.3/drivers/i2c/busses/i2c-imx.c     2015-12-18 10:39:44.971158318 -0800
+@@ -461,6 +461,8 @@
+ {
+       if (imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR) & I2SR_RXAK) {
+               dev_dbg(&i2c_imx->adapter.dev, "<%s> No ACK\n", __func__);
++              if (i2c_imx->adapter.retries)
++                      return -EAGAIN;
+               return -EIO;  /* No ACK */
+       }
+ 
+@@ -1010,6 +1012,10 @@
+       i2c_imx->adapter.nr             = pdev->id;
+       i2c_imx->adapter.dev.of_node    = pdev->dev.of_node;
+       i2c_imx->base                   = base;
++      if (of_machine_is_compatible("gw,ventana") && phy_addr == 0x021a0000) {
++              dev_info(&pdev->dev, "Adding retries for Ventana GSC\n");
++              i2c_imx->adapter.retries = 3;
++      }
+ 
+       /* Get I2C clock */
+       i2c_imx->clk = devm_clk_get(&pdev->dev, NULL);