Commit 8d48fdf6 authored by Michał Sroczyński's avatar Michał Sroczyński Committed by Greg Kroah-Hartman
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USB: PL2303: correctly handle baudrates above 115200 



PL2303: correctly handle baudrates above 115200

Signed-off-by: default avatarMichal Sroczynski <msroczyn@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 35da4137

drivers/usb/serial/pl2303.c

+22 −4
Original line number Diff line number Diff line
@@ -342,10 +342,28 @@ static void pl2303_set_termios(struct tty_struct *tty, 
				baud = 6000000;

		}

		dbg("%s - baud set = %d", __func__, baud);

		if (baud <= 115200) {

			buf[0] = baud & 0xff;

			buf[1] = (baud >> 8) & 0xff;

			buf[2] = (baud >> 16) & 0xff;

			buf[3] = (baud >> 24) & 0xff;

		} else {

			/* apparently the formula for higher speeds is:

			 * baudrate = 12M * 32 / (2^buf[1]) / buf[0]

			 */

			unsigned tmp = 12*1000*1000*32 / baud;

			buf[3] = 0x80;

			buf[2] = 0;

			buf[1] = (tmp >= 256);

			while (tmp >= 256) {

				tmp >>= 2;

				buf[1] <<= 1;

			}

			if (tmp > 256) {

				tmp %= 256;

			}

			buf[0] = tmp;

		}

	}



	/* For reference buf[4]=0 is 1 stop bits */