On 7/7/08, Grant Likely <[EMAIL PROTECTED]> wrote:
> On Mon, Jul 7, 2008 at 1:49 AM, Andre Schwarz
> <[EMAIL PROTECTED]> wrote:
> > David,
> >
> > thanks - removed "device_type" from the DMA controller.
> >
> > Which nodes actually require "device_type" and which don't ?
> >
> > Is there some general rule ?
>
>
> Segher, David;
>
> In OF, what is the purpose of device_type? From what I understand
> right now, each value of device_type claims a software interface that
> the device supports. So for example, device_type = "serial" means
> that firmware supports using the device as a serial port, correct?
> So, similarly, if OF did not have a driver for the device, then the
> presence a device_type property would be a bug, right?
>
> Does device_type indicated any other information other than firmware
> driver interface?
>
> I had an epiphany about device_type this weekend (and by epiphany, I
> mean realizing my own stupidity). If I'm correct about the above
> questions, then that would mean it is *always* a bug to have a
> device_type property in .dts file because there is no firmware
> interface. So, it seems to me that we shouldn't just be eliminating
> undefined device_type values, but also eliminate the ones that are
> defined in OF because .dts users do not support the firmware driver
> interface.
>
> Am I correct?
>
> The only situation where I can see it being appropriate to specify
> device_type is to work around older bindings that are ambiguous with
> their other properties.
I experimented with this on my own trees.
device_type = "serial";
Is current required on the boot console or it will disappear.
--
Jon Smirl
[EMAIL PROTECTED]
_______________________________________________
Linuxppc-dev mailing list
Linuxppc-dev@ozlabs.org
https://ozlabs.org/mailman/listinfo/linuxppc-dev
