Revert "usb: pl2303: increase the allowed baud rate range for the divisor based encoding method"

This reverts commit b5c16c6a031c52cc4b7dda6c3de46462fbc92eab.

Revert all of the pl2303 changes that went into 3.12-rc1 and -rc2 as
they cause regressions on some versions of the chip.  This will all be
revisited for later kernel versions when we can figure out how to handle
this in a way that does not break working devices.

Reported-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Frank Schäfer <fschaefer.oss@googlemail.com>
Acked-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/serial/pl2303.c

@@ -324,20 +324,12 @@ static int pl2303_baudrate_encode_divisor(int baud, enum pl2303_type type,
 	 */
 	unsigned int A, B;
 
-	/*
-	 * NOTE: The Windows driver allows maximum baud rates of 110% of the
-	 * specified maximium value.
-	 * Quick tests with early (2004) HX (rev. A) chips suggest, that even
-	 * higher baud rates (up to the maximum of 24M baud !) are working fine,
-	 * but that should really be tested carefully in "real life" scenarios
-	 * before removing the upper limit completely.
-	 * Baud rates smaller than the specified 75 baud are definitely working
-	 * fine.
-	 */
+	/* Respect the specified baud rate limits */
+	baud = max_t(int, baud, 75);
 	if (type == HX)
-		baud = min_t(int, baud, 6000000 * 1.1);
+		baud = min_t(int, baud, 6000000);
 	else
-		baud = min_t(int, baud, 1228800 * 1.1);
+		baud = min_t(int, baud, 1228800);
 	/* Determine factors A and B */
 	A = 0;
 	B = 12000000 * 32 / baud;  /* 12MHz */