Input: sermouse - improve protocol error recovery

When using MS protocol the driver should wait for a byte with
bit 6 set before assuming that it sees beginning of a data packet.
This should allow driver better cope with lost bytes and prevent
spurious left/right button events when serial communication is
disturbed by a CPU-hungry real-time process.

Also fix some formatting.

Signed-off-by: Peter Osterlund <petero2@telia.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

diff --git a/drivers/input/mouse/sermouse.c b/drivers/input/mouse/sermouse.c
index a85d74710b44cd3d474ba79562e698005420880b..0ac448a82bde3bbd0193d098c0d62be10528634f 100644 (file)
--- a/drivers/input/mouse/sermouse.c
+++ b/drivers/input/mouse/sermouse.c
@@ -69,7 +69,8 @@ static void sermouse_process_msc(struct sermouse *sermouse, signed char data)
        switch (sermouse->count) {
 
                case 0:
-                       if ((data & 0xf8) != 0x80) return;
+                       if ((data & 0xf8) != 0x80)
+                               return;
                        input_report_key(dev, BTN_LEFT,   !(data & 4));
                        input_report_key(dev, BTN_RIGHT,  !(data & 1));
                        input_report_key(dev, BTN_MIDDLE, !(data & 2));
@@ -107,7 +108,10 @@ static void sermouse_process_ms(struct sermouse *sermouse, signed char data)
        struct input_dev *dev = sermouse->dev;
        signed char *buf = sermouse->buf;
 
-       if (data & 0x40) sermouse->count = 0;
+       if (data & 0x40)
+               sermouse->count = 0;
+       else if (sermouse->count == 0)
+               return;
 
        switch (sermouse->count) {
 
@@ -169,7 +173,8 @@ static void sermouse_process_ms(struct sermouse *sermouse, signed char data)
 
                case 5:
                case 7: /* Ignore anything besides MZ++ */
-                       if (sermouse->type != SERIO_MZPP) break;
+                       if (sermouse->type != SERIO_MZPP)
+                               break;
 
                        switch (buf[1]) {
 
@@ -206,13 +211,16 @@ static irqreturn_t sermouse_interrupt(struct serio *serio,
 {
        struct sermouse *sermouse = serio_get_drvdata(serio);
 
-       if (time_after(jiffies, sermouse->last + HZ/10)) sermouse->count = 0;
+       if (time_after(jiffies, sermouse->last + HZ/10))
+               sermouse->count = 0;
+
        sermouse->last = jiffies;
 
        if (sermouse->type > SERIO_SUN)
                sermouse_process_ms(sermouse, data);
        else
                sermouse_process_msc(sermouse, data);
+
        return IRQ_HANDLED;
 }