USB: ftdi_sio: fix resolution of 2232H baud rate dividers

The 2232H high speed baud rates also support fractional baud
rate divisors, but when the performing the divisions before
the multiplication, the fractional bits are lost.

Signed-off-by: Daniel Glöckner <dg@emlix.com>
Acked-by: Mark Adamson <mark.adamson@ftdichip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index a2668d08926096f827de803289fa7029d7475671..71a0f99023bdfbdf5dd8ba5b9012d4a7939fb6fd 100644 (file)
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -955,7 +955,7 @@ static __u32 ftdi_2232h_baud_base_to_divisor(int baud, int base)
        int divisor3;
 
        /* hi-speed baud rate is 10-bit sampling instead of 16-bit */
-       divisor3 = (base / 10 / baud) * 8;
+       divisor3 = base * 8 / (baud * 10);
 
        divisor = divisor3 >> 3;
        divisor |= (__u32)divfrac[divisor3 & 0x7] << 14;