drivers:misc:ti-st: handle delayed tty receive

When certain technologies shutdown their interface without waiting for
the acknowledgement from the chip. The receive_buf from the TTY would be
invoked a while after the relevant technology is unregistered.

This patch introduces a new flag "is_registered" which maintains the
state of protocols BT, FM or GPS and thereby removes the need to clear
the protocol data from ST when protocols gets unregistered.

This fixes corner cases when HCI RESET is sent down from bluetooth stack
and the receive_buf is called from tty after 250ms before which
bluetooth would have unregistered from the system.
OR - when FM application decides to close down the device without
sending a power-off FM command resulting in some RDS data or interrupt
data coming in after the driver is unregistered.

Signed-off-by: Pavan Savoy <pavan_savoy@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 2 insertions, 1 deletions

diff --git a/include/linux/ti_wilink_st.h b/include/linux/ti_wilink_st.h
index 7071ec5d0118..b004e557caa9 100644
--- a/include/linux/ti_wilink_st.h
+++ b/include/linux/ti_wilink_st.h
@@ -140,12 +140,12 @@ extern long st_unregister(struct st_proto_s *);
  */
 struct st_data_s {
         unsigned long st_state;
-        struct tty_struct *tty;
         struct sk_buff *tx_skb;
 #define ST_TX_SENDING   1
 #define ST_TX_WAKEUP    2
         unsigned long tx_state;
         struct st_proto_s *list[ST_MAX_CHANNELS];
+        bool is_registered[ST_MAX_CHANNELS];
         unsigned long rx_state;
         unsigned long rx_count;
         struct sk_buff *rx_skb;
@@ -155,6 +155,7 @@ struct st_data_s {
         unsigned char   protos_registered;
         unsigned long ll_state;
         void *kim_data;
+        struct tty_struct *tty;
 };
 
 /*