Re: [PATCH v2 5/8] v4l: Switch from V4L2 OF not V4L2 fwnode API

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On Mon, Apr 10, 2017 at 12:59:36PM +0300, Sakari Ailus wrote:
> Hi Mika and Laurent,
> 
> On 04/10/17 12:21, Mika Westerberg wrote:
> > On Sat, Apr 08, 2017 at 01:55:15AM +0300, Sakari Ailus wrote:
> >>> My ACPI knowledge is limited, but don't ACPI nodes have 4 character names that 
> >>> can be combined in a string to create a full path ?
> >>
> >> There is something, yes, but the ACPI framework currently has no such
> >> functionality. I believe it could be implemented though. Cc Mika.
> > 
> > All ACPI node names are 32-bit integers and those are combined to form a
> > path, like \_SB.PCI0.I2C0 and so on. A single ACPI node name cannot be
> > larger than 4 chars, though.
> 
> On OF, each node has a full_node string attached to it. You could
> produce a similar string on ACPI, it is not currently done. Adding such
> a string to each fwnode would require some extra memory as well. I
> wonder if that could be a Kconfig option.
> 
> It would help debugging though.
> 
> Providing this information to the user space has been proposed as well:
> Devicetree spec defines the syntax for such strings. The user can use
> that information for recognising a particular device in the system.
> 
> The ACPI spec does, too, but it is limited to ACPI nodes and does not
> address hierarchical data extensions. We'd define the syntax for those
> ourselves.
> 
> Mika: what do you think?

There is a function acpi_get_name() which you can use to extract the
full name of the node. Why not investigate how to use that instead of
duplicating the name in an ACPI node.
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