On 2016年09月18日 05:49, Wolfram Sang wrote:
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().
I think the is one totally different issue with i2c-pasemi, in which
PCI device prior to probed occupied bus number supposed to be used by
i2c-pasemi.
For my case, i2c-kempld register dynamically itself by default,
consequently it would occupied i2c bus 0 and cause to fails for adding
new i2c bus with i2c_add_number_adpater(0).
although i2c-kempld provide variable 'i2c_bus' to control bus
assignment, it isso inconvenient we have to manually modify it to avoid
possible conflict. so the reasonable solution looks like:
i2c-kempld.c
i2c->adap.nr = i2c_bus;
if (i2c_bus >= -1) /* using pci id to register if default=-1
for dynamic assignment*/
i2c->adap.n = pdev->id;
ret = i2c_add_numbered_adapter(&i2c->adap);
how do you like it?
Yadi
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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