diff --git a/src/soc/amd/glinda/espi_util.c b/src/soc/amd/glinda/espi_util.c
index d26a29f..067a722 100644
--- a/src/soc/amd/glinda/espi_util.c
+++ b/src/soc/amd/glinda/espi_util.c
@@ -4,7 +4,7 @@
 #include <soc/espi.h>
 #include <types.h>
 
-#define ESPI_CNTRL_REGISTER	0x10
+#define ESPI_CNTRL_REGISTER	0x10 /* SPI register, not eSPI register! */
 #define  LOCK_SPIX10_BIT2	BIT(3)
 #define  ESPI_MUX_SPI1		BIT(2)
 #define  ROM_ADDR_WR_PROT	BIT(1)
diff --git a/src/soc/amd/mendocino/espi_util.c b/src/soc/amd/mendocino/espi_util.c
index 20db1b6..ffc8169 100644
--- a/src/soc/amd/mendocino/espi_util.c
+++ b/src/soc/amd/mendocino/espi_util.c
@@ -4,7 +4,7 @@
 #include <soc/espi.h>
 #include <types.h>
 
-#define ESPI_CNTRL_REGISTER	0x10
+#define ESPI_CNTRL_REGISTER	0x10 /* SPI register, not eSPI register! */
 #define  LOCK_SPIX10_BIT2	BIT(3)
 #define  ESPI_MUX_SPI1		BIT(2)
 #define  ROM_ADDR_WR_PROT	BIT(1)
diff --git a/src/soc/amd/phoenix/espi_util.c b/src/soc/amd/phoenix/espi_util.c
index 20db1b6..ffc8169 100644
--- a/src/soc/amd/phoenix/espi_util.c
+++ b/src/soc/amd/phoenix/espi_util.c
@@ -4,7 +4,7 @@
 #include <soc/espi.h>
 #include <types.h>
 
-#define ESPI_CNTRL_REGISTER	0x10
+#define ESPI_CNTRL_REGISTER	0x10 /* SPI register, not eSPI register! */
 #define  LOCK_SPIX10_BIT2	BIT(3)
 #define  ESPI_MUX_SPI1		BIT(2)
 #define  ROM_ADDR_WR_PROT	BIT(1)