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authorUwe Bonnes <bon@elektron.ikp.physik.tu-darmstadt.de>2011-07-22 10:41:15 +0200
committerGreg Kroah-Hartman <gregkh@suse.de>2011-08-08 12:34:48 -0700
commit0ee404ccf1c63aa25363940d474c3c03f8d7e882 (patch)
treea59624c6f19fa45254546cd15f9fb0d3572ca523 /drivers
parent17d3e145a4ad680b3d1b1c30d0696a5bbb2b65c4 (diff)
usb: serial: ftdi_sio.c: For the FT232H FTDI_SIO_SET_BAUDRATE_REQUEST, index needs to be shifted too
the recent addition of the FT232H showed that baudrate was set wrong. See gmane.linux.usb.general: "[ftdi_sio] FT232H support". With the old code, the MSB of the 4 encoded fractional divider bits and more important the clock predivider bits got lost. Adding the FT232H to the code patch were these bits are shifted solves the problem. I verified baud rates with a scope now. I suspect, that the BM device probably needs these bits shifted too. But there is no predivider bit, so this is not obvious, and a missing MSB of the encoded fractional divider only shifts the resulting baudrate minimal. The AM has only 3 bits of encoded fractional divider, so it is not impacted. I have no BM device to test, so I only added a comment and left the code for the BM untouched. Signed-off-by: Uwe Bonnes <bon@elektron.ikp.physik.tu-darmstadt.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/usb/serial/ftdi_sio.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index 9afb36143738..7d42f61bd7ad 100644
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -1205,7 +1205,10 @@ static int change_speed(struct tty_struct *tty, struct usb_serial_port *port)
urb_index_value = get_ftdi_divisor(tty, port);
urb_value = (__u16)urb_index_value;
urb_index = (__u16)(urb_index_value >> 16);
- if (priv->interface) { /* FT2232C */
+ if ((priv->chip_type == FT2232C) || (priv->chip_type == FT2232H) ||
+ (priv->chip_type == FT4232H) || (priv->chip_type == FT232H)) {
+ /* Probably the BM type needs the MSB of the encoded fractional
+ * divider also moved like for the chips above. Any infos? */
urb_index = (__u16)((urb_index << 8) | priv->interface);
}