Hi Jean,
On 01/26/2014 12:13 PM, Jean Delvare wrote:
Hi Guenter,
Adding Wei Ni to Cc, as he provided the commit which causes problem.
On Sun, 26 Jan 2014 11:28:16 -0800, Guenter Roeck wrote:
Hi,
the lm90 driver is no longer working on PCs with the 3.13 kernel ... or at least not without
special configuration.
This is what I get if I try to instantiate a device on it (max6695):
i2c 1-0018: Driver lm90 requests probe deferral
i2c i2c-1: new_device: Instantiated device max6695 at 0x18
The regulator core always returns -EPROBE_DEFER if the platform does not support devicetree
and if the regulator it is looking for does not exist. Since the driver now requires a mandatory
regulator (commit 3e0f964f2ad - hwmon: (lm90) Add power control), and the regulator it requests
does not exist on a PC, the result is not really surprising. I thought the regulator core would
realize that it has to return a dummy regulator, but apparently that is not the case, or I don't
know how to configure it.
Any idea what I might need to do to get it working ?
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.
Maybe there is some configuration option, or maybe something needs to be
configured from user space. I found neither. In the first case, we should create
a dependency for the LM90 driver; in the latter case, we would have to make sure
that it is well documented (I'd grumble on that, though - it would result in
never ending trouble for us, having to repeatedly explain how this is now
supposed to work).
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.
Guenter
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