i2c: imx: Don't generate STOP condition if arbitration has been lost

If arbitration is lost, the master automatically changes to slave mode.
I2SR_IBB may or may not be reset by hardware. Raising a STOP condition
by resetting I2CR_MSTA has no effect and will not clear I2SR_IBB.

So calling i2c_imx_bus_busy() is not required and would busy-wait until
timeout.

Signed-off-by: Christian Eggers <ceggers@arri.de>
Tested (not extensively) on Vybrid VF500 (Toradex VF50):
Tested-by: Krzysztof Kozlowski <krzk@kernel.org>
Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
Cc: stable@vger.kernel.org # Requires trivial backporting, simple remove
                           # the 3rd argument from the calls to
                           # i2c_imx_bus_busy().
Signed-off-by: Wolfram Sang <wsa@kernel.org>

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index a2abae1..e6f8d6e 100644 (file)
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -615,6 +615,8 @@ static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx, bool atomic)
                /* Stop I2C transaction */
                dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
                temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
+               if (!(temp & I2CR_MSTA))
+                       i2c_imx->stopped = 1;
                temp &= ~(I2CR_MSTA | I2CR_MTX);
                if (i2c_imx->dma)
                        temp &= ~I2CR_DMAEN;
@@ -778,9 +780,12 @@ static int i2c_imx_dma_read(struct imx_i2c_struct *i2c_imx,
                 */
                dev_dbg(dev, "<%s> clear MSTA\n", __func__);
                temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
+               if (!(temp & I2CR_MSTA))
+                       i2c_imx->stopped = 1;
                temp &= ~(I2CR_MSTA | I2CR_MTX);
                imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
-               i2c_imx_bus_busy(i2c_imx, 0, false);
+               if (!i2c_imx->stopped)
+                       i2c_imx_bus_busy(i2c_imx, 0, false);
        } else {
                /*
                 * For i2c master receiver repeat restart operation like:
@@ -905,9 +910,12 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs,
                                dev_dbg(&i2c_imx->adapter.dev,
                                        "<%s> clear MSTA\n", __func__);
                                temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
+                               if (!(temp & I2CR_MSTA))
+                                       i2c_imx->stopped =  1;
                                temp &= ~(I2CR_MSTA | I2CR_MTX);
                                imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
-                               i2c_imx_bus_busy(i2c_imx, 0, atomic);
+                               if (!i2c_imx->stopped)
+                                       i2c_imx_bus_busy(i2c_imx, 0, atomic);
                        } else {
                                /*
                                 * For i2c master receiver repeat restart operation like: