Re: [PATCH] Add MPC5200B base board mvBC-P

["Jon Smirl" <jonsmirl@gmail.com>]

On 7/7/08, Grant Likely <grant.likely@secretlab.ca> wrote:
> On Mon, Jul 7, 2008 at 1:49 AM, Andre Schwarz
>  <andre.schwarz@matrix-vision.de> 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
jonsmirl@gmail.com