On Tuesday 01 April 2008 15:16, Grant Likely wrote:

On Mon, Mar 31, 2008 at 10:39 AM, Laurent Pinchart
[off-list ref] wrote:

quoted

 Signed-off-by: Laurent Pinchart [off-list ref]
 ---
  Documentation/powerpc/booting-without-of.txt |   13 ++++++++++++-
  1 files changed, 12 insertions(+), 1 deletions(-)

 diff --git a/Documentation/powerpc/booting-without-of.txt=20
 b/Documentation/powerpc/booting-without-of.txt=20
 index 7b4e8a7..3e1963b 100644
 --- a/Documentation/powerpc/booting-without-of.txt
 +++ b/Documentation/powerpc/booting-without-of.txt
 @@ -57,7 +57,8 @@ Table of Contents
       n) 4xx/Axon EMAC ethernet nodes
       o) Xilinx IP cores
       p) Freescale Synchronous Serial Interface
 -         q) USB EHCI controllers
 +      q) USB EHCI controllers
 +      r) Memory-mapped RAM & ROM

   VII - Specifying interrupt information for devices
     1) interrupts property
 @@ -2816,6 +2817,16 @@ platforms are moved over to use the
 flattened-device-tree model.=20
                   big-endian;
           };

 +   r) Memory-mapped RAM & ROM
 +
 +    Dedicated RAM and ROM chips are often used as storage for tempora=

ry

quoted

 or=20
 +    permanent data in embedded devices. Possible usage include
 non-volatile=20
 +    storage in battery-backed SRAM, semi-permanent storage in dedicat=

ed

quoted

 SRAM=20
 +    to preserve data accross reboots and firmware storage in dedicated
 ROM.=20
 +
 +     - name : should be either "ram" or "rom"
 +     - reg : Address range of the RAM/ROM chip
 +

=20
No compatible prop?  How does the OS know what the node is to be used for?

If I understood Sergei's arguments properly, the device tree should describ=
e=20
device properties and not their intended usage. With generic devices such a=
s=20
RAM chips, platform code is responsible for binding the device to the=20
appropriate driver (mtd-ram for instance).

Cheers,

=2D-=20
Laurent Pinchart
CSE Semaphore Belgium

Chauss=E9e de Bruxelles, 732A
B-1410 Waterloo
Belgium

T +32 (2) 387 42 59
=46 +32 (2) 387 42 75