--- zzzz-none-000/linux-3.10.107/drivers/misc/ti-st/st_core.c	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/drivers/misc/ti-st/st_core.c	2021-02-04 17:41:59.000000000 +0000
@@ -22,7 +22,6 @@
 #define pr_fmt(fmt)	"(stc): " fmt
 #include <linux/module.h>
 #include <linux/kernel.h>
-#include <linux/init.h>
 #include <linux/tty.h>
 
 #include <linux/seq_file.h>
@@ -154,8 +153,9 @@
 				(st_gdata->list[i]->priv_data, err);
 			pr_info("protocol %d's cb sent %d\n", i, err);
 			if (err) { /* cleanup registered protocol */
-				st_gdata->protos_registered--;
 				st_gdata->is_registered[i] = false;
+				if (st_gdata->protos_registered)
+					st_gdata->protos_registered--;
 			}
 		}
 	}
@@ -343,12 +343,26 @@
 			/* Unknow packet? */
 		default:
 			type = *ptr;
-			if (st_gdata->list[type] == NULL) {
-				pr_err("chip/interface misbehavior dropping"
-					" frame starting with 0x%02x", type);
-				goto done;
 
+			/* Default case means non-HCILL packets,
+			 * possibilities are packets for:
+			 * (a) valid protocol -  Supported Protocols within
+			 *     the ST_MAX_CHANNELS.
+			 * (b) registered protocol - Checked by
+			 *     "st_gdata->list[type] == NULL)" are supported
+			 *     protocols only.
+			 *  Rules out any invalid protocol and
+			 *  unregistered protocols with channel ID < 16.
+			 */
+
+			if ((type >= ST_MAX_CHANNELS) ||
+					(st_gdata->list[type] == NULL)) {
+				pr_err("chip/interface misbehavior: "
+						"dropping frame starting "
+						"with 0x%02x\n", type);
+				goto done;
 			}
+
 			st_gdata->rx_skb = alloc_skb(
 					st_gdata->list[type]->max_frame_size,
 					GFP_ATOMIC);
@@ -446,6 +460,13 @@
  * - TTY layer when write's finished
  * - st_write (in context of the protocol stack)
  */
+static void work_fn_write_wakeup(struct work_struct *work)
+{
+	struct st_data_s *st_gdata = container_of(work, struct st_data_s,
+			work_write_wakeup);
+
+	st_tx_wakeup((void *)st_gdata);
+}
 void st_tx_wakeup(struct st_data_s *st_data)
 {
 	struct sk_buff *skb;
@@ -562,7 +583,9 @@
 			if ((st_gdata->protos_registered != ST_EMPTY) &&
 			    (test_bit(ST_REG_PENDING, &st_gdata->st_state))) {
 				pr_err(" KIM failure complete callback ");
+				spin_lock_irqsave(&st_gdata->lock, flags);
 				st_reg_complete(st_gdata, err);
+				spin_unlock_irqrestore(&st_gdata->lock, flags);
 				clear_bit(ST_REG_PENDING, &st_gdata->st_state);
 			}
 			return -EINVAL;
@@ -638,14 +661,12 @@
 		return -EPROTONOSUPPORT;
 	}
 
-	st_gdata->protos_registered--;
+	if (st_gdata->protos_registered)
+		st_gdata->protos_registered--;
+
 	remove_channel_from_table(st_gdata, proto);
 	spin_unlock_irqrestore(&st_gdata->lock, flags);
 
-	/* paranoid check */
-	if (st_gdata->protos_registered < ST_EMPTY)
-		st_gdata->protos_registered = ST_EMPTY;
-
 	if ((st_gdata->protos_registered == ST_EMPTY) &&
 	    (!test_bit(ST_REG_PENDING, &st_gdata->st_state))) {
 		pr_info(" all chnl_ids unregistered ");
@@ -798,8 +819,12 @@
 	/* don't do an wakeup for now */
 	clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
 
-	/* call our internal wakeup */
-	st_tx_wakeup((void *)st_gdata);
+	/*
+	 * schedule the internal wakeup instead of calling directly to
+	 * avoid lockup (port->lock needed in tty->ops->write is
+	 * already taken here
+	 */
+	schedule_work(&st_gdata->work_write_wakeup);
 }
 
 static void st_tty_flush_buffer(struct tty_struct *tty)
@@ -810,7 +835,7 @@
 	kfree_skb(st_gdata->tx_skb);
 	st_gdata->tx_skb = NULL;
 
-	tty->ops->flush_buffer(tty);
+	tty_driver_flush_buffer(tty);
 	return;
 }
 
@@ -867,6 +892,9 @@
 			pr_err("unable to un-register ldisc");
 		return err;
 	}
+
+	INIT_WORK(&st_gdata->work_write_wakeup, work_fn_write_wakeup);
+
 	*core_data = st_gdata;
 	return 0;
 }
@@ -893,5 +921,3 @@
 		kfree(st_gdata);
 	}
 }
-
-