1 files changed, 38 insertions, 2 deletions

diff --git a/drivers/usb/serial/pl2303.c b/drivers/usb/serial/pl2303.c
index 4cbe59c4ae7f..82055b07e02c 100644
--- a/drivers/usb/serial/pl2303.c
+++ b/drivers/usb/serial/pl2303.c
@@ -528,6 +528,12 @@ static void pl2303_set_termios(struct tty_struct *tty,
         int baud;
         int i;
         u8 control;
+        const int baud_sup[] = { 75, 150, 300, 600, 1200, 1800, 2400, 3600,
+                                 4800, 7200, 9600, 14400, 19200, 28800, 38400,
+                                 57600, 115200, 230400, 460800, 614400,
+                                 921600, 1228800, 2457600, 3000000, 6000000 };
+        int baud_floor, baud_ceil;
+        int k;
 
         dbg("%s -  port %d", __func__, port->number);
 
@@ -573,9 +579,39 @@ static void pl2303_set_termios(struct tty_struct *tty,
                 dbg("%s - data bits = %d", __func__, buf[6]);
         }
 
+        /* For reference buf[0]:buf[3] baud rate value */
+        /* NOTE: Only the values defined in baud_sup are supported !
+         *       => if unsupported values are set, the PL2303 seems to use
+         *          9600 baud (at least my PL2303X always does)
+         */
         baud = tty_get_baud_rate(tty);
-        dbg("%s - baud = %d", __func__, baud);
+        dbg("%s - baud requested = %d", __func__, baud);
         if (baud) {
+                /* Set baudrate to nearest supported value */
+                for (k=0; k<ARRAY_SIZE(baud_sup); k++) {
+                        if (baud_sup[k] / baud) {
+                                baud_ceil = baud_sup[k];
+                                if (k==0) {
+                                        baud = baud_ceil;
+                                } else {
+                                        baud_floor = baud_sup[k-1];
+                                        if ((baud_ceil % baud)
+                                            > (baud % baud_floor))
+                                                baud = baud_floor;
+                                        else
+                                                baud = baud_ceil;
+                                }
+                                break;
+                        }
+                }
+                if (baud > 1228800) {
+                        /* type_0, type_1 only support up to 1228800 baud */
+                        if (priv->type != HX)
+                                baud = 1228800;
+                        else if (baud > 6000000)
+                                baud = 6000000;
+                }
+                dbg("%s - baud set = %d", __func__, baud);
                 buf[0] = baud & 0xff;
                 buf[1] = (baud >> 8) & 0xff;
                 buf[2] = (baud >> 16) & 0xff;
@@ -648,7 +684,7 @@ static void pl2303_set_termios(struct tty_struct *tty,
                 pl2303_vendor_write(0x0, 0x0, serial);
         }
 
-        /* FIXME: Need to read back resulting baud rate */
+        /* Save resulting baud rate */
         if (baud)
                 tty_encode_baud_rate(tty, baud, baud);