ARM: 8335/1: Documentation: DT bindings: Tegra AHB: document the legacy base address

Documentation: DT bindings: Tegra AHB: require the legacy base address for existing chips

Per Stephen Warren, note in the Tegra AHB DT binding documentation
that we specifically deprecate any attempt to use the IP block's
actual hardware base address, and advocate the use of the legacy
"off-by-four" address in the 'regs' property, for Tegra chips with
existing upstream Linux DT files that include a Tegra AHB node.  This
patch updates the documentation accordingly.

Changing the existing kernel DT data isn't under consideration because
Linux kernel DT data policy is to preserve compatibility between newer
DT data files and older kernels.  However, this additional step of
changing the documentation should discourage others from sending
kernel patches to try to change the legacy kernel DT data.
Furthermore, for out-of-tree software (such as bootloaders or other
operating systems) that may rely on Linux kernel DT binding
documentation as an ABI (but not the Linux kernel DT data itself),
such a change may allow future convergence with the Linux kernel DT
data without additional code changes.

Signed-off-by: Paul Walmsley <[email protected]>
Cc: Paul Walmsley <[email protected]>
Cc: Stephen Warren <[email protected]>
Cc: Alexandre Courbot <[email protected]>
Cc: Eduardo Valentin <[email protected]>
Cc: Ian Campbell <[email protected]>
Cc: Kumar Gala <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Pawel Moll <[email protected]>
Cc: Rob Herring <[email protected]>
Cc: Thierry Reding <[email protected]>
Cc: [email protected]
Cc: [email protected]
Acked-by: Stephen Warren <[email protected]>
Signed-off-by: Russell King <[email protected]>

0 files changed, 0 insertions, 0 deletions