i2c: mxc: add a condition in case the parameter is NULL

This could avoid executing the code that only applies to i.MX platforms.

The bus_i2c_init() is called before relocation and will assgin value
to a static variable. If U-Boot is then still running in a flash
device, it's theoretically not allowed to write data to flash without
an erasing operation. For i.MX platforms, the U-Boot is always running
in DDR.

Actually it causes asynchronous error when the ARM64 system error
report is enabled and the flash write protect is set.

Signed-off-by: Gong Qianyu <Qianyu.Gong@freescale.com>
Reviewed-by: Heiko Schocher <hs@denx.de>

diff --git a/drivers/i2c/mxc_i2c.c b/drivers/i2c/mxc_i2c.c
index fa4c82f1a25b0775c7e69e97dbc178fd32f06539..b2d15c9b6a82e201d48ef501657919aae9643047 100644 (file)
--- a/drivers/i2c/mxc_i2c.c
+++ b/drivers/i2c/mxc_i2c.c
@@ -581,8 +581,16 @@ void bus_i2c_init(int index, int speed, int unused,
                return;
        }
 
-       mxc_i2c_buses[index].idle_bus_fn = idle_bus_fn;
-       mxc_i2c_buses[index].idle_bus_data = idle_bus_data;
+       /*
+        * Warning: Be careful to allow the assignment to a static
+        * variable here. This function could be called while U-Boot is
+        * still running in flash memory. So such assignment is equal
+        * to write data to flash without erasing.
+        */
+       if (idle_bus_fn)
+               mxc_i2c_buses[index].idle_bus_fn = idle_bus_fn;
+       if (idle_bus_data)
+               mxc_i2c_buses[index].idle_bus_data = idle_bus_data;
 
        ret = enable_i2c_clk(1, index);
        if (ret < 0) {