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 <johan@kernel.org>

diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index 4168801..d61703d 100644 (file)
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -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