spelling: s/usefull/useful/

Signed-off-by: Adrian Bunk <[e-mail]>

Documentation/networking/sk98lin.txt

···
 This parameters is only relevant if auto-negotiation for this port is 
 not set to "Sense". If auto-negotiation is set to "On", all three values
 are possible. If it is set to "Off", only "Full" and "Half" are allowed.
-This parameter is usefull if your link partner does not support all
+This parameter is useful if your link partner does not support all
 possible combinations.
 
 Flow Control

Documentation/power/swsusp.txt

···
 
 cat `cat /proc/[0-9]*/maps | grep / | sed 's:.* /:/:' | sort -u` > /dev/null
 
-after resume. swapoff -a; swapon -a may also be usefull.
+after resume. swapoff -a; swapon -a may also be useful.
 
 Q: What happens to devices during swsusp? They seem to be resumed
 during system suspend?
···
 A: No, it should work okay, as long as your app does not mlock()
 it. Just prepare big enough swap partition.
 
-Q: What information is usefull for debugging suspend-to-disk problems?
+Q: What information is useful for debugging suspend-to-disk problems?
 
 A: Well, last messages on the screen are always useful. If something
 is broken, it is usually some kernel driver, therefore trying with as

Makefile

···
 # If it is set to "silent_", nothing wil be printed at all, since
 # the variable $(silent_cmd_cc_o_c) doesn't exist.
 #
-# A simple variant is to prefix commands with $(Q) - that's usefull
+# A simple variant is to prefix commands with $(Q) - that's useful
 # for commands that shall be hidden in non-verbose mode.
 #
 #	$(Q)ln $@ :<

arch/xtensa/kernel/time.c

···
 	if ((signed long)(get_ccount() - next) > 0)
 		goto again;
 
-	/* Allow platform to do something usefull (Wdog). */
+	/* Allow platform to do something useful (Wdog). */
 
 	platform_heartbeat();
 

drivers/media/radio/radio-sf16fmr2.c

···
 static int radio_nr = -1;
 
 /* hw precision is 12.5 kHz
- * It is only usefull to give freq in intervall of 200 (=0.0125Mhz),
+ * It is only useful to give freq in intervall of 200 (=0.0125Mhz),
  * other bits will be truncated
  */
 #define RSF16_ENCODE(x)	((x)/200+856)

drivers/net/sk98lin/skdim.c

···
                 /*
                 ** The number of interrupts per sec is the same as expected.
                 ** Evalulate the descriptor-ratio. If it has changed, a resize 
-                ** in the moderation timer might be usefull
+                ** in the moderation timer might be useful
                 */
                 if (M_DIMINFO.AutoSizing) {
                     ResizeDimTimerDuration(pAC);

drivers/net/sk98lin/skge.c

···
  * Description:
  *	This function is called if an ioctl is issued on the device.
  *	There are three subfunction for reading, writing and test-writing
- *	the private MIB data structure (usefull for SysKonnect-internal tools).
+ *	the private MIB data structure (useful for SysKonnect-internal tools).
  *
  * Returns:
  *	0, if everything is ok

drivers/net/sk98lin/skgepnmi.c

···
  * Description:
  *	Calls a general sub-function for all this stuff. The preset does
  *	the same as a set, but returns just before finally setting the
- *	new value. This is usefull to check if a set might be successfull.
+ *	new value. This is useful to check if a set might be successfull.
  *	If the instance -1 is passed, an array of values is supposed and
  *	all instances of the OID will be set.
  *
···
  * Description:
  *	Calls a general sub-function for all this stuff. The preset does
  *	the same as a set, but returns just before finally setting the
- *	new value. This is usefull to check if a set might be successfull.
+ *	new value. This is useful to check if a set might be successfull.
  *	If the instance -1 is passed, an array of values is supposed and
  *	all instances of the OID will be set.
  *
···
  * Description:
  *	Calls a general sub-function for all this set stuff. The preset does
  *	the same as a set, but returns just before finally setting the
- *	new value. This is usefull to check if a set might be successfull.
+ *	new value. This is useful to check if a set might be successfull.
  *	The sub-function runs through the IdTable, checks which OIDs are able
  *	to set, and calls the handler function of the OID to perform the
  *	preset. The return value of the function will also be stored in
···
  *
  * Description:
  *	The COMMON module only tells us if the mode is half or full duplex.
- *	But in the decade of auto sensing it is usefull for the user to
+ *	But in the decade of auto sensing it is useful for the user to
  *	know if the mode was negotiated or forced. Therefore we have a
  *	look to the mode, which was last used by the negotiation process.
  *

drivers/w1/Kconfig

···
 config W1
 	tristate "Dallas's 1-wire support"
 	---help---
-	  Dallas's 1-wire bus is usefull to connect slow 1-pin devices
+	  Dallas's 1-wire bus is useful to connect slow 1-pin devices
 	  such as iButtons and thermal sensors.
 
 	  If you want W1 support, you should say Y here.