diff --git a/Documentation/scsi/hpsa.txt b/Documentation/scsi/hpsa.txt
index dca6583..b14e6ee 100644
--- a/Documentation/scsi/hpsa.txt
+++ b/Documentation/scsi/hpsa.txt
@@ -28,6 +28,12 @@
 nor supported by HP with this driver.  For older Smart Arrays, the cciss
 driver should still be used.
 
+The "hpsa_simple_mode=1" boot parameter may be used to prevent the driver from
+putting the controller into "performant" mode.  The difference is that with simple
+mode, each command completion requires an interrupt, while with "performant mode"
+(the default, and ordinarily better performing) it is possible to have multiple
+command completions indicated by a single interrupt.
+
 HPSA specific entries in /sys
 -----------------------------