diff options
Diffstat (limited to 'drivers/usb')
| -rw-r--r-- | drivers/usb/serial/cp210x.c | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c index eac7ccaa3c85..8ba1005f6a53 100644 --- a/drivers/usb/serial/cp210x.c +++ b/drivers/usb/serial/cp210x.c @@ -301,6 +301,14 @@ static struct usb_serial_driver * const serial_drivers[] = { #define CONTROL_WRITE_RTS 0x0200 /* + * CP210X_PURGE - 16 bits passed in wValue of USB request. + * SiLabs app note AN571 gives a strange description of the 4 bits: + * bit 0 or bit 2 clears the transmit queue and 1 or 3 receive. + * writing 1 to all, however, purges cp2108 well enough to avoid the hang. + */ +#define PURGE_ALL 0x000f + +/* * cp210x_get_config * Reads from the CP210x configuration registers * 'size' is specified in bytes. @@ -475,7 +483,14 @@ static int cp210x_open(struct tty_struct *tty, struct usb_serial_port *port) static void cp210x_close(struct usb_serial_port *port) { + unsigned int purge_ctl; + usb_serial_generic_close(port); + + /* Clear both queues; cp2108 needs this to avoid an occasional hang */ + purge_ctl = PURGE_ALL; + cp210x_set_config(port, CP210X_PURGE, &purge_ctl, 2); + cp210x_set_config_single(port, CP210X_IFC_ENABLE, UART_DISABLE); } |
