On Wed, Jan 20, 2016 at 11:53 AM, Rob Herring [off-list ref] wrote:

On Wed, Jan 20, 2016 at 12:47 PM, John Stultz [off-list ref] wrote:
The question here really is will we ever need additional data for each
mode (in the DT) besides "magic". We can do some amount of extending
the property like allowing more that single 32-bit value. We can't mix
strings and integers though. If we don't need that, then lets go with
the more concise approach. This isn't really an evolving area.
Selecting boot mode/device has existed for a long time on PCs (it is
fixed list in the IPMI spec for example). So I can't imagine that we'd
have to extend this, but I'd like to hear thoughts on it. You had
mentioned the Galaxy Nexus having a value and a string, but I'd find
it surprising if the bootloader actually uses the string.

So I've been told the galaxy nexus and possibly other older TI
hardware used only a string.

And the HTC implementations I've seen have code for both a string and
command to be placed, but usually don't actually copy anything to the
string address (which suggest its not used by the bootloader, as you
note).

Either way, we'd have to extend or implement a new driver, but that's
a bridge I think we can cross later when we see such hardware support
upstream (rather then try to create a super driver that handles
everything a creative firmware developer could come up with).

thanks
-john