input: i8042 possible bug

Here is an extract from drivers/input/serio/i8042.c:

static int i8042_flush(void)
{
	unsigned long flags;
	unsigned char data, str;
	int i = 0;

	spin_lock_irqsave(&i8042_lock, flags);

	while (((str = i8042_read_status()) & I8042_STR_OBF) && (i < I8042_BUFFER_SIZE)) {
		udelay(50);
		data = i8042_read_data();
		i++;
		dbg("%02x <- i8042 (flush, %s)\n",
		    data, str & I8042_STR_AUXDATA ? "aux" : "kbd");
	}

	spin_unlock_irqrestore(&i8042_lock, flags);

	return i;
}

static int i8042_controller_check(void)
{
	if (i8042_flush() == I8042_BUFFER_SIZE) {

Doesn't it panic needlessly, while the buffer was initially full?

		pr_err("No controller found\n");
		return -ENODEV;
	}

	return 0;
}

On Tue, Sep 03, 2013 at 09:39:10PM +0400, Andrey Moiseev wrote:

Here is an extract from drivers/input/serio/i8042.c:

quoted

static int i8042_flush(void)
{
	unsigned long flags;
	unsigned char data, str;
	int i = 0;

	spin_lock_irqsave(&i8042_lock, flags);

	while (((str = i8042_read_status()) & I8042_STR_OBF) && (i < I8042_BUFFER_SIZE)) {
		udelay(50);
		data = i8042_read_data();
		i++;
		dbg("%02x <- i8042 (flush, %s)\n",
		    data, str & I8042_STR_AUXDATA ? "aux" : "kbd");
	}

	spin_unlock_irqrestore(&i8042_lock, flags);

	return i;
}

static int i8042_controller_check(void)
{
	if (i8042_flush() == I8042_BUFFER_SIZE) {

Doesn't it panic needlessly, while the buffer was initially full?

It appears so. We probably want to change it to return -1 if we still
see OBF after fetching I8042_BUFFER_SIZE characters.

Thanks.

-- 
Dmitry