Re: Pinmux with device tree

On Thu, 19 May 2011, Mitch Bradley wrote:

On 5/19/2011 10:36 AM, Nicolas Pitre wrote:

quoted

On Thu, 19 May 2011, Mitch Bradley wrote:

quoted

So, in my world, space is always an issue.

I'm guessing that in such a scenario you have the kernel stored
somewhere else, right?  You therefore simply have to store the FDT data
along with the kernel in that other location, and have your boot
firmware load an additional and relatively small file.

There is no stored FDT.  The firmware generates the device tree dynamically
from a combination of static information and dynamic probing.

quoted

It is very important that the DT data be updateable independently from
the firmware, just like the kernel is.  Ideally, the DT would indeed be
exported by the firmware, but that works only in theory.  In practice it
_will_ contain bugs that might be visible only after kernel development
has progressed, and therefore it is primordial to be able to update it
easily.  Hence in practice it is best if it is not exported/generated by
the firmware directly.

In our world it works in practice.  We control the hardware, firmware, and OS
releases.  In many cases, a firmware update is less expensive than an OS
release by several orders of magnitude.

I don't think this can be said for ARM in general though.
This is where all the recent surge of activity around DT comes from.


Nicolas