On Sat, Jun 9, 2012 at 12:53 AM, Seth Forshee <seth.forshee@xxxxxxxxxxxxx> wrote: > > On Thu, Jun 07, 2012 at 02:56:58PM -0500, Seth Forshee wrote: > > > Or, alternatively, we could actually report negative values to > > > userspace in this case: > > > > > > y = (y <= 6143) ? y : (y - 8192); > > > > Well, they won't be negative anymore when userspace sees them ;) > > > > But yeah, either of these should work. I don't feel like it's necessary > > since this is apparently a one-off problem on aging hardware, and since > > Windows also doesn't seem to be using the portion of the touchpad > > reporting the out of range values (although humorously I can get the > > pointer to jump sometimes under Windows too). Between the two > > implementations you suggest I'd feel more comfortable with the latter, > > as it should leave the values reported unchanged for other hardware. > > > > I do have one question I'd still like to clear up. Am I correct in > > interpreting the Synaptics documentation to say that the touchpads > > should never report values greater than 6143, even for models that > > report the maximum possible x/y values? That's what I think it's saying, > > but I also feel like there's a little ambiguity on the point. Especially > > since I'm already seeing values outside of the documented range :) > > The following is working fine for me, if you think this would be > preferable. The only downside I see is that if there are touchpads out > there that exceed 6143 then this is likely to cause them to start > behaving oddly. > > > From 2664e38cbebe7e9de652d22d9bc408dd210e6c0b Mon Sep 17 00:00:00 2001 > From: Seth Forshee <seth.forshee@xxxxxxxxxxxxx> > Date: Fri, 8 Jun 2012 10:19:39 -0500 > Subject: [PATCH] Input: synaptics - handle negative values on the y axis > > The touchpad on the Acer Aspire One D250 will report out of range values > in the extreme lower portion of the touchpad. These appear as abrupt > changes in the values reported by the hardware from very low values to > very high values, which can cause unexpected vertical jumps in the > position of the mouse pointer. > > What seems to be happening is that the value is wrapping to a negative > 13-bit value, which is being truncated to the 12-bit range reported in > the touchpad packets. In order to deal with this, convert values outside > the maximum y axis value specified by synaptics to the appropriate > negative value. > > BugLink: http://bugs.launchpad.net/bugs/1001251 > Cc: stable@xxxxxxxxxxxxxxx > Signed-off-by: Seth Forshee <seth.forshee@xxxxxxxxxxxxx> Reviewed-by: Daniel Kurtz <djkurtz@xxxxxxxxxxxx> > --- > drivers/input/mouse/synaptics.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/drivers/input/mouse/synaptics.c > b/drivers/input/mouse/synaptics.c > index e07eb9b..7dc1bd5 100644 > --- a/drivers/input/mouse/synaptics.c > +++ b/drivers/input/mouse/synaptics.c > @@ -40,6 +40,7 @@ > * Note that newer firmware allows querying device for maximum useable > * coordinates. > */ > +#define YMAX 6143 > #define XMIN_NOMINAL 1472 > #define XMAX_NOMINAL 5472 > #define YMIN_NOMINAL 1408 > @@ -555,6 +556,15 @@ static int synaptics_parse_hw_state(const unsigned > char buf[], > hw->right = (buf[0] & 0x02) ? 1 : 0; > } > > + /* > + * Some Synaptics touchpads have been known to wrap negative > + * on the y axis. These appear to be a 13-bit negative numbers > + * truncated to a 12-bit value. To work around this, treat any > + * value above the upper limit defined by Synaptics as actually > + * being a negative 13-bit value. > + */ > + hw->y = (hw->y <= YMAX) ? hw->y : (hw->y - 8192); > + > return 0; > } > > -- > 1.7.9.5 > -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
