LPC31 EHCI: Seems to work after re-ordering some initialization logic

arch/arm/src/lpc31xx/lpc31_ehci.c

@@ -4307,7 +4307,7 @@ FAR struct usbhost_connection_s *lpc31_ehci_initialize(int controller)
    * SLOM   Not used in host mode.
    * SDIS = 1, Stream disable mode.  Eliminates overruns/underruns at
    *        the expense of some performance.
-   * VBPS = 1, off chip power source
+   * VBPS = 1, off-chip power source
    */
 
   putreg32(USBHOST_USBMODE_CMHOST | USBHOST_USBMODE_SDIS | USBHOST_USBMODE_VBPS,
@@ -4323,6 +4323,14 @@ FAR struct usbhost_connection_s *lpc31_ehci_initialize(int controller)
       return NULL;
     }
 
+  /* Re-program the USB host controller.  As implemented, lpc31_reset()
+   * requires the host mode setup in order to work.  However, we lose the
+   * host configuration in the reset.
+   */
+
+  putreg32(USBHOST_USBMODE_CMHOST | USBHOST_USBMODE_SDIS | USBHOST_USBMODE_VBPS,
+           LPC31_USBDEV_USBMODE);
+
   /* "In order to initialize the host controller, software should perform the
    *  following steps:
    *

configs/olimex-lpc-h3131/README.txt

@@ -686,3 +686,10 @@ Configurations
          Application Configuration -> System Add-Ons
            CONFIG_SYSTEM_USBMONITOR=y
            CONFIG_SYSTEM_USBMONITOR_INTERVAL=1
+
+       NOTE:  I have found that if you enable USB DEBUG and/or USB tracing,
+       the resulting image requires to much memory to execute out of
+       internal SRAM.  I was able to get the configurations to run out of
+       SRAM with debug/tracing enabled by carefully going through the
+       configuration and reducing stack sizes, disabling unused OS features,
+       disabling un-necessary NSH commands, etc.