[PATCH] i2c: imx: add retries for i2c-0 on Ventana boards

Tim Harvey
2016-07-07T13:58:12Z

Gateworks Ventana IMX6 based boards have a Gateworks System Controller [1]
(gsc) device that can NAK i2c transactions when its busy in an ADC loop. As
this is always on i2c-0 we will add retries for that bus for any Ventana
board.

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
---
drivers/i2c/busses/i2c-imx.c | 12 ++++++++++++
1 file changed, 12 insertions(+)

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 1844bc9..aec71c3 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -460,6 +460,8 @@ static int i2c_imx_acked(struct imx_i2c_struct *i2c_imx)
{
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 -ENXIO; /* No ACK */
}

@@ -1068,6 +1070,16 @@ static int i2c_imx_probe(struct platform_device *pdev)
i2c_imx->adapter.dev.of_node = pdev->dev.of_node;
i2c_imx->base = base;

+ /*
+ * The Gateworks Ventana has an i2c based system controller on i2c-0
+ * which emulates several standard i2c devices with existing drivers.
+ * That device can NAK when its in an ADC loop. Add bus retries.
+ */
+ 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);
if (IS_ERR(i2c_imx->clk)) {
--
1.9.1