LPC31 EHCI: Make stream disable a configurable option

arch/arm/src/lpc31xx/Kconfig

@@ -253,6 +253,18 @@ if LPC31_USBOTG && USBHOST
 
 menu "USB host controller driver (HCD) options"
 
+config LPC31_EHCI_SDIS
+	bool "Stream disable"
+	default n
+	---help---
+		Selecting this option ensures that overruns/underruns of the latency
+		FIFO are eliminated for low bandwidth systems where the RX and TX
+		buffers are sufficient to contain the entire packet. Enabling stream
+		disable also has the effect of ensuring the the TX latency is filled
+		to capacity before the packet is launched onto the USB.
+
+		Note: Time duration to pre-fill the FIFO becomes significant when stream disable is active.
+
 config LPC31_EHCI_NQHS
 	int "Number of Queue Head (QH) structures"
 	default 4

arch/arm/src/lpc31xx/lpc31_ehci.c

@@ -4310,7 +4310,7 @@ FAR struct usbhost_connection_s *lpc31_ehci_initialize(int controller)
    * VBPS = 1, off-chip power source
    */
 
-  putreg32(USBHOST_USBMODE_CMHOST | USBHOST_USBMODE_SDIS | USBHOST_USBMODE_VBPS,
+  putreg32(USBHOST_USBMODE_CMHOST /* | USBHOST_USBMODE_SDIS */ | USBHOST_USBMODE_VBPS,
            LPC31_USBDEV_USBMODE);
 
   /* Host Controller Initialization. Paragraph 4.1 */

fs/fs_inode.c

@@ -61,7 +61,7 @@
  * because there can be cycles.  For example, it may be necessary to destroy
  * a block driver inode on umount() after a removable block device has been
  * removed.  In that case umount() hold the inode semaphore, but the block
- * driver may callback to unregister_blockdriver() after the un-mount, 
+ * driver may callback to unregister_blockdriver() after the un-mount,
  * requiring the seamphore again.
  */
 
@@ -187,7 +187,7 @@ void fs_initialize(void)
   (void)sem_init(&g_inode_sem.sem, 0, 1);
   g_inode_sem.holder = NO_HOLDER;
   g_inode_sem.count  = 0;
-  
+
   /* Initialize files array (if it is used) */
 
 #ifdef CONFIG_HAVE_WEAKFUNCTIONS
@@ -218,7 +218,7 @@ void inode_semtake(void)
       /* Yes... just increment the count */
 
       g_inode_sem.count++;
-      DEBUGASSERT(g_inode_sem.count > 0); 
+      DEBUGASSERT(g_inode_sem.count > 0);
     }
 
   /* Take the semaphore (perhaps waiting) */