On Thu, 5 Jun 2014 09:20:08 +0100, Lee Jones [off-list ref] wrote:

On Thu, 05 Jun 2014, Mika Westerberg wrote:

quoted

On Wed, Jun 04, 2014 at 02:28:20PM +0100, Lee Jones wrote:

quoted

On Wed, 04 Jun 2014, Mika Westerberg wrote:

quoted

On Wed, Jun 04, 2014 at 02:37:42PM +0200, Rafael J. Wysocki wrote:

quoted

On Wednesday, June 04, 2014 01:09:56 PM Lee Jones wrote:

quoted

Currently this is a helper function for the I2C subsystem to aid the
matching of non-standard compatible strings and devices which use DT
and/or ACPI, but do not supply any nodes (see: [1] Method 4).  However,
it has been made more generic as it can be used to only make one call
for drivers which support any mixture of OF, ACPI and/or I2C matching.

The initial aim is for of_match_device() to be replaced by this call
in all I2C device drivers.

[1] Documentation/i2c/instantiating-devices

Signed-off-by: Lee Jones <redacted>

Mika, can you please have a look at this, please?

I don't see any fundamental problems with this wrt. ACPI.

That said, I find it kind of weird to have generic function that then
has knowledge of how different buses do their matching.

I would rather see something like firmware_device_match(dev) that goes
and matches from DT/ACPI and leave bus specific match to happen internal
to that bus.

Unfortunately that completely defeats the object of the patch.  When a
of_match_device() is invoked it solely looks up devices based on OF
matching, but I2C is special in that devices can be registered via
sysfs, thus will no have device node.  If of_match_device() is called
in one of these instances it will fail.  The idea of this patch is to
generify the matching into something does has the knowledge to firstly
attempt a traditional match, and if that fails will fall back to a
special i2c_{of,acpi}_match_device() which knows how to deal with
node-less registration.

OK, then but since this is now I2C specific, why call it device_match()
instead of something like i2c_device_match()? Or do you have plans to

So in an early incarnation of the patch I did just that, and it might
not actually be such a bad idea still - I'm open to other people's
opinions on this.

quoted

add there more knowledge about other buses like SPI and PCI to name few?

... but yes, this is the new idea - that it can be expanded as required.

The whole point of this series is to deal with a special use case of i2c
that we don't need to support for the other bus types. We're having to
just through special hoops to make it work and I don't want to expand it
to other bus types if at all possible.

g.

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org ??? Open source software for ARM SoCs
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