i2c: smbus: Prepare i2c_register_spd for usage on muxed segments

If this is an adapter on a muxed bus segment, assume that each segment
is connected to a subset of the (> 8) overall memory slots. In this
case let's probe the maximum of 8 slots, however stop if the number
of overall populated slots is reached.

If we're not on a muxed segment and the total number of slots is > 8,
then warn because then not all SPD eeproms can be addressed.
Presumably the bus is muxed, but the mux config is missing.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
[wsa: removed a superfluous printout]
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

diff --git a/drivers/i2c/i2c-smbus.c b/drivers/i2c/i2c-smbus.c
index 74807c6db596d810fffe035268875a61b1074881..97f338b123b11872402df5d84ef7c20ef33454f2 100644 (file)
--- a/drivers/i2c/i2c-smbus.c
+++ b/drivers/i2c/i2c-smbus.c
@@ -351,13 +351,18 @@ void i2c_register_spd(struct i2c_adapter *adap)
        if (!dimm_count)
                return;
 
-       dev_info(&adap->dev, "%d/%d memory slots populated (from DMI)\n",
-                dimm_count, slot_count);
-
-       if (slot_count > 8) {
-               dev_warn(&adap->dev,
-                        "Systems with more than 8 memory slots not supported yet, not instantiating SPD\n");
-               return;
+       /*
+        * If we're a child adapter on a muxed segment, then limit slots to 8,
+        * as this is the max number of SPD EEPROMs that can be addressed per bus.
+        */
+       if (i2c_parent_is_i2c_adapter(adap)) {
+               slot_count = 8;
+       } else {
+               if (slot_count > 8) {
+                       dev_warn(&adap->dev,
+                                "More than 8 memory slots on a single bus, contact i801 maintainer to add missing mux config\n");
+                       return;
+               }
        }
 
        /*