Attempt to fix and document interactions between suspend/resume and pccardc

power x 0.

pccardc power x 0 used to disable the slot.  But a suspend/resume
would reactivate the pccard.  It no longer does that.  Now the
disabling of the slot is sticy until it is reset with power x 1 or the
card is ejected.  This seems closer to correct behavior to me.

o Process all card state changes the same using pccard_do_stat_change().
o Cleanup disabling the card so that we can preserve the state after
  the change.  Basically, don't set it to empty as often as we do.
o On suspend, the new state is "empty" and the laststate is "suspend"
o Document state machine with a diagram of states and edges.  The
  edges are labeld to tell the reader what event causes the external
  state changes.
o "machdep.pccard.pcic_resume_reset" may be obsolete now.  We always
  call the bridge driver's resume method on resume now.  Otherwise cards
  won't automatically show up.  If it needs to stay, I'll add it back.

1 files changed, 28 insertions, 0 deletions

diff --git a/sys/pccard/cardinfo.h b/sys/pccard/cardinfo.h
index b4926e7..0c48451 100644
--- a/sys/pccard/cardinfo.h
+++ b/sys/pccard/cardinfo.h
@@ -58,7 +58,35 @@
 
 /*
  *	Slot states for PIOCGSTATE
+ *
+ *	Here's a state diagram of all the possible states:
+ *
+ *			      power x 1
+ *			 -------------------
+ *			/		    \
+ *		       /       		     v
+ *    resume  	+----------+   power x 0   +----------+
+ *	------->| inactive |<--------------| filled   |
+ *     /       	+----------+         	   +----------+
+ *    /	    	  / 	\    	      	    ^  	|
+ *  nil <---------  	 \   	  insert or |  	| suspend or
+ *	     suspend	  \   	  power x 1 |  	| eject
+ *			   \   	       	    |  	v
+ *	    		    \	    	   +----------+
+ *     	       	       	     ------------->|  empty   |
+ *     	       	       	       eject	   +----------+
+ *
+ *	Note, the above diagram is for the state.  On suspend, the laststate
+ * gets set to suspend to tell pccardd what happened.  Also the nil state
+ * means that when the no state change has happened.
+ *
+ * Some might argue that inactive should be sticky forever and
+ * eject/insert shouldn't take it out of that state.  They might be
+ * right.  On the other hand, some would argue that eject resets all
+ * state.  They might be right.  They both can't be right.  The above
+ * represents a reasonable compromise between the two.
  */
+
 enum cardstate { noslot, empty, suspend, filled, inactive };
 
 /*