On 01/19/2016 02:46 PM, [email protected] wrote:
> I'm having a problem on a number of systems where the IPMI driver isn't able 
> to find the ACPI IPMI device.
>
> This is happening because the ACPI scan is attaching the acpi_pnp handler to 
> the ACPI IPMI device, which is happening because the IPMI device has a _CID 
> of PNP0C01 in addition to an _HID of IPI0001.  This is a problem because 
> acpi_scan_attach_handler() doesn't know about the IPMI drivers (ipmi_si / 
> ipmi_ssif), which don't register as PNP or ACPI drivers, but instead expect 
> the ACPI scan find no applicable driver and thus create a platform device.

I recently pulled out the pnp code in ipmi_si in favour of a platform 
device.  The trouble was that you couldn't register both the ipmi_si and 
ipmi_ssif driver with IPI0001 (even though they were in different 
spaces) because IPI0001 was hard-coded into the acpi_pnp tables.  This 
fix prevented having to update a lot of firmware.

Plus I was under the impression that this was the right thing to do, 
anyway.  Perhaps it wasn't, but I didn't get a comment from the 
linux-acpi list when I submitted it (twice).

> This could be fixed pretty easily by modifying acpi_scan_attach_handler() to 
> make it return 0 without attaching a handler to devices that have a _HID of 
> IPI0001 when the kernel has an IPMI driver available (if, say, 
> CONFIG_IPMI_SI, CONFIG_IPMI_SI_MODULE, CONFIG_IPMI_SSIF, or 
> CONFIG_IPMI_SSIF_MODULE are defined)... but would this be accepted?

That sounds like a bad hack to me.

>    Or is this something that will require reworking the IPMI drivers?  Or is 
> there another way?

The question in my mind is why the IPMI device has a _CID of PNP0C01 (or 
is it PNP0c01?  That's the only thing I found.).    From what I can tell 
from the spec, PNP0c01 is a "system board", and Linux has it as a 
"memory controller", neither of which is really applicable.

But I admit that I don't know very much about these things.  I believe 
the right place to fix this is the driver, if we can.  I'm hoping for a 
simple solution.

-corey

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