summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorJohan Hovold <johan@kernel.org>2021-01-27 12:00:28 +0100
committerJohan Hovold <johan@kernel.org>2021-02-01 14:06:27 +0100
commit1ef268039b79945a9284dbc34eedcbad21415106 (patch)
tree50fceae98cdad97c3236160366fdb92b01079409
parentUSB: serial: ftdi_sio: fix FTX sub-integer prescaler (diff)
downloadlinux-1ef268039b79945a9284dbc34eedcbad21415106.tar.xz
linux-1ef268039b79945a9284dbc34eedcbad21415106.zip
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>
-rw-r--r--drivers/usb/serial/ftdi_sio.c16
1 files changed, 8 insertions, 8 deletions
diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index 4168801b9595..d61703d858a1 100644
--- 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