> > The eg20t driver uses i2c_add_numbered_adapter() to register adapter: > > > > pch_adap->nr = i; > > ret = i2c_add_numbered_adapter(pch_adap); > > > > Variable i is assigned to 0, it means that i2c_eg20t is the first adapter > > by default. if another adapter registers before eg20t, above code return > > error for index conflict: > > > > i2c_eg20t 0000:05:0c.2: pch_i2c_probe :i2c_add_adapter[ch:0] FAILED > > i2c_eg20t: probe of 0000:05:0c.2 failed with error -16 > > > > So, we can replace i2c_add_numbered_adapter() with i2c_add_adapter() > > interface.since it dynamically allocates the index number. > > This does the exact opposite of: > > commit 07e8a51ff68353e01d795cceafbac9f54c49132b > Author: Feng Tang <feng.tang@xxxxxxxxx> > Date: Thu Jan 12 15:38:02 2012 +0800 > > i2c-eg20t: use i2c_add_numbered_adapter to get a fixed bus number We have the same problem with i2c-pasemi: http://www.spinics.net/lists/linux-i2c/msg25761.html PCI + i2c_add_numbered_adapter + another device adding i2c busses And we cannot simply change back to i2c_add_adapter() because it will regress on those systems which originally wanted to have i2c_add_numbered_adapter(). > Looking at > > commit 03bde7c31a360f814ca42101d60563b1b803dca1 > Author: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx> > Date: Thu Mar 12 17:17:59 2015 +0100 > > i2c: busses with dynamic ids should start after fixed ids for DT > > it could be that you need to set some OF attribute to reserve i2c bus > numbers <= 1 for static usage. Assuming you use OF. Or is it automatic, > Wolfram? No, you need to define an alias in the devicetree. I don't think this platform is a DT user, though? > If not, it may make sense to add a helper function exposing > __i2c_first_dynamic_bus_num to drivers (something like > i2c_is_dynamic_bus_num().) After all, i2c_add_numbered_adapter() mostly > makes sense if static i2c device definitions exist. If not, > i2c_add_adapter() is just as good. So something like: > > if (i2c_is_dynamic_bus_num(i)) > ret = i2c_add_adapter(pch_adap); > else { > pch_adap->nr = i; > ret = i2c_add_numbered_adapter(pch_adap); > } > > may make sense. Unless someone has a better idea. Interesting idea. Need to think about it some more. I didn't have a proper solution so far... Thanks, Wolfram
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