diff --git a/README b/README
index 68f5fb0..831c5af 100644
--- a/README
+++ b/README
@@ -746,6 +746,10 @@
 		CONFIG_PCA953X		- use NXP's PCA953X series I2C GPIO
 		CONFIG_PCA953X_INFO	- enable pca953x info command
 
+		The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
+		chip-ngpio pairs that tell the PCA953X driver the number of
+		pins supported by a particular chip.
+
 		Note that if the GPIO device uses I2C, then the I2C interface
 		must also be configured. See I2C Support, below.