Refine wordings

lkmpg.tex

@@ -1931,34 +1931,36 @@ The example below modifies the previous example to also run an additional task w
 
 \subsection{Threaded IRQ}
 
-Threaded IRQ is a mechanism to handle both top-half and bottom-half of an IRQ at once.
-A threaded IRQ splits one handler into two: one for the top-half, the other for the bottom-half.
-Those two handlers are registered at once by \cpp|request_threaded_irq()|.
+Threaded IRQ is a mechanism to organize both top-half and bottom-half of an IRQ at once.
+A threaded IRQ splits the one handler in \cpp|request_irq()| into two: one for the top-half, the other for the bottom-half.
+The \cpp|request_threaded_irq()| is the function for using threaded IRQs.
+Two handlers are registered at once in the \cpp|request_threaded_irq()|.
 
+Those two handlers run in different context.
 The top-half handler runs in interrupt context.
 It's the equivalence of the handler passed to the \cpp|request_irq()|.
 The bottom-half handler on the other hand runs in its own thread.
-This thread is created on registration of a threaded IRQ. Its sole purpose is to run this bottom-half handler.
+This thread is created on registration of a threaded IRQ.
+Its sole purpose is to run this bottom-half handler.
 This is where a threaded IRQ is ``threaded''.
-
-Whether the bottom-half handler will be invoked is determined by the return value of the top-half handler.
-If \cpp|IRQ_WAKE_THREAD| is returned, that bottom-half serving thread will wake up.
+If \cpp|IRQ_WAKE_THREAD| is returned by the top-half handler, that bottom-half serving thread will wake up.
 The thread then runs the bottom-half handler.
 
 Here is an example of how to do the same thing as before, with top and bottom halves, but using threads.
 
 \samplec{examples/bh_threaded.c}
 
-\cpp|request_threaded_irq()| only takes one additional parameter than the \cpp|request_irq()| -- the bottom-half handling function that runs in its own thread.
+A threaded IRQ is registered using \cpp|request_threaded_irq()|.
+This function only takes one additional parameter than the \cpp|request_irq()| -- the bottom-half handling function that runs in its own thread.
 In this example it is the \cpp|button_bottom_half()|.
 Usage of other parameters are the same as \cpp|request_irq()|.
 
 Presence of both handlers is not mandatory.
 If either of them is not needed, pass the \cpp|NULL| instead.
-A \cpp|NULL| top-half handler implicitly means doing nothing but waking up the bottom-half serving thread; A \cpp|NULL| bottom-half handler will have the same effect as \cpp|request_irq()|.
+A \cpp|NULL| top-half handler implicitly means doing nothing but waking up the bottom-half serving thread (for running the bottom-half handler); A \cpp|NULL| bottom-half handler would have the same effect as if \cpp|request_irq()| were used.
 In fact, this is how \cpp|request_irq()| is implemented.
 
-Note that passing \cpp|NULL| as both handlers is considered an error and will make registration fail.
+Note that passing \cpp|NULL| to both handlers is considered an error and will make registration fail.
 
 \section{Virtual Input Device Driver}
 \label{sec:vinput}