Document special nature of setCS in comments

SPI.cpp

@@ -306,6 +306,7 @@ bool SPIClass::pinIsChipSelect(uint8_t pin1, uint8_t pin2)
 	return true;
 }
 
+// setCS() is not intended for use from normal Arduino programs/sketches.
 uint8_t SPIClass::setCS(uint8_t pin)
 {
 	switch (pin) {
@@ -453,6 +454,7 @@ bool SPI1Class::pinIsChipSelect(uint8_t pin1, uint8_t pin2)
 	return true;
 }
 
+// setCS() is not intended for use from normal Arduino programs/sketches.
 uint8_t SPI1Class::setCS(uint8_t pin)
 {
 	switch (pin) {
@@ -585,6 +587,7 @@ bool SPI2Class::pinIsChipSelect(uint8_t pin1, uint8_t pin2)
 	return true;
 }
 
+// setCS() is not intended for use from normal Arduino programs/sketches.
 uint8_t SPI2Class::setCS(uint8_t pin)
 {
 	switch (pin) {
@@ -669,6 +672,7 @@ const uint8_t SPISettings::br_clock_table[30] = {
 	SPI_BR_SPPR(5) | SPI_BR_SPR(6)
 };
 
+// setCS() is not intended for use from normal Arduino programs/sketches.
 uint8_t SPIClass::setCS(uint8_t pin)
 {
 	switch (pin) {
@@ -692,6 +696,7 @@ void SPI1Class::end() {
 	SPI1_C1 = 0;
 }
 
+// setCS() is not intended for use from normal Arduino programs/sketches.
 uint8_t SPI1Class::setCS(uint8_t pin)
 {
 	switch (pin) {

SPI.h

@@ -588,6 +588,8 @@ public:
 	// return true if both pin1 and pin2 have independent chip select capability
 	static bool pinIsChipSelect(uint8_t pin1, uint8_t pin2);
 	// configure a pin for chip select and return its SPI_MCR_PCSIS bitmask
+	// setCS() is a special function, not intended for use from normal Arduino
+	// programs/sketches.  See the ILI3941_t3 library for an example.
 	static uint8_t setCS(uint8_t pin);
 
 private:
@@ -782,6 +784,8 @@ public:
 	// return true if both pin1 and pin2 have independent chip select capability
 	static bool pinIsChipSelect(uint8_t pin1, uint8_t pin2);
 	// configure a pin for chip select and return its SPI_MCR_PCSIS bitmask
+	// setCS() is a special function, not intended for use from normal Arduino
+	// programs/sketches.  See the ILI3941_t3 library for an example.
 	static uint8_t setCS(uint8_t pin);
 
 private:
@@ -970,6 +974,8 @@ public:
 	// return true if both pin1 and pin2 have independent chip select capability
 	static bool pinIsChipSelect(uint8_t pin1, uint8_t pin2);
 	// configure a pin for chip select and return its SPI_MCR_PCSIS bitmask
+	// setCS() is a special function, not intended for use from normal Arduino
+	// programs/sketches.  See the ILI3941_t3 library for an example.
 	static uint8_t setCS(uint8_t pin);
 
 private:
@@ -1268,6 +1274,8 @@ public:
 	// return true if both pin1 and pin2 have independent chip select capability
 	static bool pinIsChipSelect(uint8_t pin1, uint8_t pin2) { return false; }
 	// configure a pin for chip select and return its SPI_MCR_PCSIS bitmask
+	// setCS() is a special function, not intended for use from normal Arduino
+	// programs/sketches.  See the ILI3941_t3 library for an example.
 	static uint8_t setCS(uint8_t pin);
 
 private:
@@ -1442,6 +1450,8 @@ public:
 	// return true if both pin1 and pin2 have independent chip select capability
 	static bool pinIsChipSelect(uint8_t pin1, uint8_t pin2) { return false; }
 	// configure a pin for chip select and return its SPI_MCR_PCSIS bitmask
+	// setCS() is a special function, not intended for use from normal Arduino
+	// programs/sketches.  See the ILI3941_t3 library for an example.
 	static uint8_t setCS(uint8_t pin);
 
 private: