Re: lm90 driver no longer working on PCs in 3.13

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On 01/26/2014 12:52 PM, Mark Brown wrote:
On Sun, Jan 26, 2014 at 12:44:38PM -0800, Guenter Roeck wrote:
On 01/26/2014 12:13 PM, Jean Delvare wrote:

Me, I really don't know. I seem to remember I tested Wei's patch set on
an emulated ADM1032 chip and it was working fine. So maybe it depends
on the kernel configuration, or something changed on the regulator side
meanwhile.

The regulator code changed with 3.13; the dummy regulator no longer exists,
and the functionality it provided is supposed to be handled automatically.
But that only really works on devicetree based systems and otherwise returns
-EPROBE_DEFER as mentioned above.

CONFIG_REGULATOR_DUMMY should never have been used in production, it was
a debug tool to help bringup but it broke things as often as it fixed
them particularly with init ordering which is why it generated a warning
when it was used.

The dummy driver is still there, if you're doing bringup you can hack it
in still or if you genuniely used it then specify that full constraints
are provided like the changelog says (and as I've previously said).

Another possible fix would be to have the regulator core return -ENODEV
instead of -EPROBE_DEFER on non-dt systems. No idea if this would be acceptable
or even feasible.

No, this would introduce breakage due to init ordering.


You have a solution for that in dt configurations. I don't think you have one for
non-dt systems - you simply assume that all regulators are there. For dt, you even
have a constraint to tell the kernel if regulator configurations are fully specified,
and you automatically return success if not and if a regulator does not exist.
So you know that there is a problem. For non-DT configurations you simply assume and
expect that regulators are all declared. I don't think that is a feasible approach
for non-DT systems.

Guenter


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