i2c: busses with dynamic ids should start after fixed ids for DT
authorWolfram Sang <wsa+renesas@sang-engineering.com>
Thu, 12 Mar 2015 16:17:59 +0000 (17:17 +0100)
committerWolfram Sang <wsa@the-dreams.de>
Wed, 18 Mar 2015 12:42:14 +0000 (13:42 +0100)
Make sure dynamic ids do not interfere with fixed ones and let them
start after the highest fixed id. This patch might cause different
bus-numbers than before for dynamic ids, however it fixes a bug. Assume:

- fixed id0 defers probe
- fixed id1 succeeds and registers a muxed bus with dynamic id
- muxed bus gets id0
- fixed id0 wants to probe again, but its fixed id is gone now
- fixed id0 probe fails

With this patch, the fixed ids are always reserved in the DT case.
For legacy board init, we already have a mechanism like this in
i2c_register_board_info().

Reported-by: Bob Feretich <bob.feretich@rafresearch.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
drivers/i2c/i2c-core.c

index 57a86f4aab43ec04af62b2712fd7b376c3791ea5..fe80f85896e267ca8dfb3c35aa07504bacfef39d 100644 (file)
@@ -1878,6 +1878,13 @@ static int __init i2c_init(void)
 {
        int retval;
 
+       retval = of_alias_get_highest_id("i2c");
+
+       down_write(&__i2c_board_lock);
+       if (retval >= __i2c_first_dynamic_bus_num)
+               __i2c_first_dynamic_bus_num = retval + 1;
+       up_write(&__i2c_board_lock);
+
        retval = bus_register(&i2c_bus_type);
        if (retval)
                return retval;