Re: [PATCH] Input: byd - enable absolute mode

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

Hi Richard,

On Mon, Feb 22, 2016 at 08:44:51PM -0800, Richard Pospesel wrote:
> Hi Dmitry,
> 
> 
> On 02/22/2016 12:05 PM, Dmitry Torokhov wrote:
> >Hi Chris,
> >
> >On Thu, Feb 18, 2016 at 12:07:52AM +0000, Chris Diamand wrote:
> >>+
> >>+	serio_continue_rx(psmouse->ps2dev.serio);
> >>  }
> >>
> >>  static psmouse_ret_t byd_process_byte(struct psmouse *psmouse)
> >>  {
> >>-	struct input_dev *dev = psmouse->dev;
> >>+	struct byd_data *priv = psmouse->private;
> >>+	u32 now = jiffies_to_msecs(jiffies);
> >>  	u8 *pkt = psmouse->packet;
> >>
> >>  	if (psmouse->pktcnt > 0 && !(pkt[0] & PS2_ALWAYS_1)) {
> >>@@ -102,53 +292,33 @@ static psmouse_ret_t byd_process_byte(struct psmouse *psmouse)
> >>
> >>  	/* Otherwise, a full packet has been received */
> >>  	switch (pkt[3]) {
> >>-	case 0: {
> >>+	case BYD_PACKET_ABSOLUTE:
> >>+		/* Only use absolute packets for the start of movement. */
> >>+		if (!priv->touch) {
> >>+			priv->abs_x = pkt[1] * (BYD_PAD_WIDTH / 256);
> >>+			priv->abs_y = (255 - pkt[2]) *
> >>+				      (BYD_PAD_HEIGHT / 256);
> >>+
> >>+			/* needed to detect tap */
> >>+			if (now - priv->last_touch_time > BYD_TOUCH_TIMEOUT_MS)
> >>+				priv->touch = true;
> >
> >This is not correct: it will break when time wraps around. If you need
> >to store/compare times do it in jiffies and use
> >time_before()/time_after() API.
> >
> >But I am confused why you need this. Can you please explain?
> >
> >Thanks.
> >
> 
> This does work when time wraps around, unless I've misunderstood you (
> see: https://ideone.com/OTnMH7 ).  However, I will change this to
> jiffies since that seems to be the lingua franca for time in the
> kernel.

Please.

> 
> I went over why this particular time delta check is required earlier
> in this thread.  For brevity, I'll say this is required to allow
> "two-finger" scenario where one finger navigates, while the other
> clicks on the primary mouse button.  I can go into further detail if
> you like.

Please because I tried going back to earlier messages but I could not
find detailed explanation for the delay in reporting touch.

Thanks.

-- 
Dmitry