[patch] 2.4.0-test13-pre2: better parport_pc commentary

[patch] 2.4.0-test13-pre2: better parport_pc commentary

[Tim Waugh]

Hi Linus,

Here is a patch to make the parport_pc comments better.  No code
change.

Tim.
*/

2000-12-17  Tim Waugh  <twaugh@redhat.com>

	* drivers/parport/parport_pc.c: Better commentary.  Patch from
	R Horn.
	* drivers/parport/ChangeLog: Updated.

--- linux-2.4.0-test12/drivers/parport/parport_pc.c.commentary	Tue Dec 12 13:03:24 2000
+++ linux-2.4.0-test12/drivers/parport/parport_pc.c	Wed Dec 13 14:11:11 2000
@@ -938,13 +938,11 @@
 			/* Can't yield the port. */
 			schedule ();
 
-		/* At this point, the FIFO may already be full.
-		 * Ideally, we'd be able to tell the port to hold on
-		 * for a second while we empty the FIFO, and we'd be
-		 * able to ensure that no data is lost.  I'm not sure
-		 * that's the case. :-(  It might be that you can play
-		 * games with STB, as in the forward case; someone should
-		 * look at a datasheet. */
+		/* At this point, the FIFO may already be full. In
+                 * that case ECP is already holding back the
+                 * peripheral (assuming proper design) with a delayed
+                 * handshake.  Work fast to avoid a peripheral
+                 * timeout.  */
 
 		if (ecrval & 0x01) {
 			/* FIFO is empty. Wait for interrupt. */
@@ -976,6 +974,10 @@
 				goto false_alarm;
 			}
 
+			/* Depending on how the FIFO threshold was
+                         * set, how long interrupt service took, and
+                         * how fast the peripheral is, we might be
+                         * lucky and have a just filled FIFO. */
 			continue;
 		}
 
@@ -987,6 +989,9 @@
 			continue;
 		}
 
+		/* FIFO not filled.  We will cycle this loop for a while
+                 * and either the peripheral will fill it faster,
+                 * tripping a fast empty with insb, or we empty it. */
 		*bufp++ = inb (fifo);
 		left--;
 	}
--- linux-2.4.0-test12/drivers/parport/ChangeLog.commentary	Wed Dec 13 14:17:10 2000
+++ linux-2.4.0-test12/drivers/parport/ChangeLog	Wed Dec 13 14:17:26 2000
@@ -0,0 +1,4 @@
+2000-12-17  R Horn  <rjh@world.std.com>
+
+	* parport_pc.c: Some commentary changes.
+
-
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