Re: [PATCH 1/2] powerpc: document the MPIC device tree binding

On 01/19/2011 04:14 PM, Yoder Stuart-B08248 wrote:

quoted

+** Optional properties:
+
+   - no-reset : The presence of this property indicates that the MPIC
+                should not be reset during runtime initialization.
+   - protected-sources : Specifies a list of interrupt sources that are
+ not
+                         available for use and whose corresponding
+ vectors
+                         should not be initialized.  A typical use case
+ for
+                         this property is in AMP systems where multiple
+                         independent operating systems need to share
+ the MPIC
+                         without clobbering each other.

Is "protected-sources" really needed for AMP systems to
tell the OSes not to clobber each other?  Won't each
OS be given a device tree with only its interrupt
sources?  ...so you know what you are allowed to touch.

This was discussed a little bit already [1, 2].  The MPIC driver 
currently initializes the VECPRI register for all interrupt sources, 
which can lead to the aforementioned clobbering.


-- 
Meador Inge     | meador_inge AT mentor.com
Mentor Embedded | http://www.mentor.com/embedded-software

[1] 
http://lists.ozlabs.org/pipermail/devicetree-discuss/2010-December/003850.html
[2] 
http://lists.ozlabs.org/pipermail/devicetree-discuss/2011-January/003936.html