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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>
This commit is contained in:
Johan Hovold 2021-01-27 12:00:28 +01:00
parent 528222d0c8
commit 1ef268039b
1 changed files with 8 additions and 8 deletions
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16
drivers/usb/serial/ftdi_sio.c
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@ -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