Use direct method for supported baud rates, otherwise use divisors.
Limit baud rate to 12 Mbaud with HX type.

This change has been tested to work with PL-2303HX at 115200, 500000,
1000000, 2000000, 2500000, 3000000 and 4000000 baud rates.

Signed-off-by: Lauri Hintsala <lauri.hints...@bluegiga.com>
---
CC: Johan Hovold <jhov...@gmail.com>
CC: Greg Kroah-Hartman <gre...@linuxfoundation.org>
CC: Frank Schäfer <fschaefer....@googlemail.com>
CC: linux-usb@vger.kernel.org

Changes since V1:
* added baud rate limit for HX

 drivers/usb/serial/pl2303.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/serial/pl2303.c b/drivers/usb/serial/pl2303.c
index b3d5a35..e84151a 100644
--- a/drivers/usb/serial/pl2303.c
+++ b/drivers/usb/serial/pl2303.c
@@ -161,6 +161,9 @@ static const struct pl2303_type_data 
pl2303_type_data[TYPE_COUNT] = {
                .max_baud_rate =        1228800,
                .quirks =               PL2303_QUIRK_LEGACY,
        },
+       [HX] = {
+               .max_baud_rate =        12000000,
+       },
 };
 
 static int pl2303_vendor_read(struct usb_serial *serial, u16 value,
@@ -394,16 +397,14 @@ static void pl2303_encode_baud_rate(struct tty_struct 
*tty,
        if (spriv->type->max_baud_rate)
                baud = min_t(speed_t, baud, spriv->type->max_baud_rate);
        /*
-        * Set baud rate to nearest supported value.
-        *
-        * NOTE: Baud rate 500k can only be set using divisors.
+        * Use direct method for supported baud rates, otherwise use divisors.
         */
        baud_sup = pl2303_get_supported_baud_rate(baud);
 
-       if (baud == 500000)
-               baud = pl2303_encode_baud_rate_divisor(buf, baud);
+       if (baud == baud_sup)
+               baud = pl2303_encode_baud_rate_direct(buf, baud);
        else
-               baud = pl2303_encode_baud_rate_direct(buf, baud_sup);
+               baud = pl2303_encode_baud_rate_divisor(buf, baud);
 
        /* Save resulting baud rate */
        tty_encode_baud_rate(tty, baud, baud);
-- 
1.9.1

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