Converting "board file" to device tree one device at a time?

[Russell King - ARM Linux]

On Fri, Jul 31, 2015 at 04:54:00PM +0200, Mason wrote:
> On 31/07/2015 11:57, Mason wrote:
> 
> > Then I set a breakpoint in of_platform_serial_probe, hoping
> > to witness the miracle... and nothing. Looks like device is
> > never registered :-(
> 
> IIUC, the kernel is supposed to parse my "uart0" node, and
> register the device. Then the platform framework should see
> that the node's "compatible" property is equal to one
> advertized by the of_platform_serial_driver, and the kernel
> should #!@& call of_platform_serial_probe? Right?!

No, it doesn't work like that.  The kernel creates platform devices
from the nodes described in the DT file, which are then used to bind
to the drivers in a very similar way to non-DT, except that if there's
an dev->of_node pointer present, the compatible property is used.  If
there are no devices being created from DT, drivers won't have anything
to bind to.

> I just can't believe how much time I've been pulling my hair
> over this trivial issue...

My /guess/ is that you have an .init_machine callback in place, but that
is not calling of_platform_populate(NULL, of_default_bus_match_table,
NULL, NULL); which means none of the DT-described devices are being
created.

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