Re: Xilinx devicetrees

["Grant Likely" <grant.likely@secretlab.ca>]

On 11/26/07, Koss, Mike (Mission Systems) <mike.koss@ngc.com> wrote:
> DL>    And once again a plea to ALWAYS make version/capabilities registers
> DL> atleast an optional part of every design.
> DL>    Embeddeding a device tree into a design might be fairly expensive. a
> DL> pair of read only 32 bit registers is damn near free - basically the
> DL> FPGA equivalent of atmost 64 diodes or resistors.
>
> SN> Actually, device trees actually seem to be cheaper (in the whole system
> sense) than such registers.  Unless there is something I don't understand?
>
> The issue here is that the hardware changed and the driver doesn't support
> it. I think this would be fixed by having information passed to the driver
> in the platform_device struct to specify information, since its not able to
> be discerned by the physical hardware information: version registers, etc.

This is exactly the information that should be encoded in the
'compatible' property of the device tree.  (instead of platform_data;
platform_data is no longer required with the of_platform bus binding)

*If* edk is generating our device tree(s) for us, *then* version
registers are not needed by Linux.

Cheers,
g.

-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.
grant.likely@secretlab.ca
(403) 399-0195