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USB: serial: ftdi_sio: restore divisor-encoding comments

PATCH New Johan Hovold 1 participant 1 message Jan 27, 2021

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Johan Hovold

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PATCH 1/1 USB: serial: ftdi_sio: restore divisor-encoding comments

Add back a few explanatory comments related to the divisor encoding which got lost in a coding-style clean up many years ago.

Signed-off-by Johan Hovold <[email protected]>
---
 drivers/usb/serial/ftdi_sio.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)
drivers/usb/serial/ftdi_sio.c +8 -8
index 94398f89e600..a6837a60c06a 100644
@@ -1153,13 +1153,13 @@ static unsigned short int ftdi_232am_baud_base_to_divisor(int baud, int base)
 	divisor = divisor3 >> 3;
 	divisor3 &= 0x7;
 	if (divisor3 == 1)
-		divisor |= 0xc000;
+		divisor |= 0xc000;	/* +0.125 */
 	else if (divisor3 >= 4)
-		divisor |= 0x4000;
+		divisor |= 0x4000;	/* +0.5 */
 	else if (divisor3 != 0)
-		divisor |= 0x8000;
+		divisor |= 0x8000;	/* +0.25 */
 	else if (divisor == 1)
-		divisor = 0;	/* special case for maximum baud rate */
+		divisor = 0;		/* special case for maximum baud rate */
 	return divisor;
 }
 

@@ -1177,9 +1177,9 @@ static u32 ftdi_232bm_baud_base_to_divisor(int baud, int base)
 	divisor = divisor3 >> 3;
 	divisor |= (u32)divfrac[divisor3 & 0x7] << 14;
 	/* Deal with special cases for highest baud rates. */
-	if (divisor == 1)
+	if (divisor == 1)		/* 1.0 */
 		divisor = 0;
-	else if (divisor == 0x4001)
+	else if (divisor == 0x4001)	/* 1.5 */
 		divisor = 1;
 	return divisor;
 }

@@ -1201,9 +1201,9 @@ static u32 ftdi_2232h_baud_base_to_divisor(int baud, int base)
 	divisor = divisor3 >> 3;
 	divisor |= (u32)divfrac[divisor3 & 0x7] << 14;
 	/* Deal with special cases for highest baud rates. */
-	if (divisor == 1)
+	if (divisor == 1)		/* 1.0 */
 		divisor = 0;
-	else if (divisor == 0x4001)
+	else if (divisor == 0x4001)	/* 1.5 */
 		divisor = 1;
 	/*
 	 * Set this bit to turn off a divide by 2.5 on baud rate generator
Signature · 1 line
2.26.2