Re: [PATCH] acpi, property: Export acpi_dev_prop_read_single call.

[David Daney]

On 08/05/2015 04:55 PM, Rafael J. Wysocki wrote:
> On Wednesday, August 05, 2015 04:17:21 PM David Daney wrote:
> > On 08/05/2015 04:23 PM, Rafael J. Wysocki wrote:
> > > On Wednesday, August 05, 2015 01:14:49 PM David Daney wrote:
> > > > On 08/05/2015 10:26 AM, David Daney wrote:
> > > > > On 08/05/2015 06:43 AM, Tomasz Nowicki wrote:
> > > > > > On 05.08.2015 15:48, Rafael J. Wysocki wrote:
> > > > > > > On Tuesday, August 04, 2015 04:01:59 PM David Daney wrote:
> > > > > > > > From: Tomasz Nowicki <tomasz.nowicki@xxxxxxxxxx>
> > > > > > > >
> > > > > > > > Fixes the following build error when building drivers as modules:
> > > > > > > >
> > > > > > > >     ERROR: "acpi_dev_prop_read_single" [drivers/net/phy/mdio-octeon.ko]
> > > > > > > > undefined!
> > > > > > > >     ERROR: "acpi_dev_prop_read_single"
> > > > > > > > [drivers/net/ethernet/cavium/thunder/thunder_bgx.ko] undefined!
> > > > > > >
> > > > > > > Can you please tell me why the drivers in question use that function
> > > > > > > directly, although they aren't supposed to?
> > > > > > >
> > > > > > > Clearly, their authors had not tried to build them as modules or they
> > > > > > > would have noticed the problem at the development stage already.
> > > > > > >
> > > > > > > What would be wrong with using the generic device properties API
> > > > > > > instead?
> > > > > > Yes, you are right. We should use:
> > > > > > int device_property_read_u64_array(struct device *dev, const char
> > > > > > *propname, u64 *val, size_t nval);
> > > > >
> > > > > Thanks all, for the review and suggestions.  We we try the suggested
> > > > > approach and see how it goes...
> > > >
> > > > Actually I don't think device_property_read_u64_array() will work.
> > > >
> > > > We are traversing a reference to a different acpi_device via
> > > > acpi_dev_get_property_reference(),
> > >
> > > Why?
> >
> > Network device has a "phy-handle" (traversed with
> > acpi_dev_get_property_reference()), and we want to get some properties
> > of that phy.
> >
> > I could turn the question around to you:  Why export
> > acpi_dev_get_property_reference()?  If there is a reason to export that,
> > then you should let people use the result.
>
> The GPIO core uses it and you *can* use the result (please see my other
> message).

It was somewhat of a rhetorical question.

I would actually like to do as you suggest, so I am looking at unwinding 
the driver code to use the interfaces you suggest.

It is a multi-step process for me though.  First I had to make the 
existing code work.  I now have it working, so next I will try to fix it.

> I wonder how does the ACPI table in question look like.  Do you have
> an acpidump output from that system by any chance?

Not handy.  I will be producing one soon though.

The good news is that I can change the firmware to make it correct if it 
has problems.


Thanks for your patience,
David Daney


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