On Thursday, October 27, 2016, Peter Hutterer <peter.hutte...@who-t.net>
wrote:
> On Wed, Oct 26, 2016 at 11:56:57PM -0700, Ping Cheng wrote:
> > On Wednesday, October 26, 2016, Peter Hutterer <peter.hutte...@who-t.net
> <javascript:;>>
> > wrote:
> >
> > > On Wed, Oct 26, 2016 at 06:24:48PM -0700, Ping Cheng wrote:
> > > > On Fri, Oct 7, 2016 at 10:25 AM, Jason Gerecke <killert...@gmail.com
> <javascript:;>
> > > <javascript:;>> wrote:
> > > > > The driver has historically normalized the pressure range of all
> kernel
> > > > > devices to 0..2047 rather than using their native range to keep
> things
> > > > > like the application of the pressure curve simple. Pens that report
> > > more
> > > > > than 2048 pressure levels are also normalized down to this range
> > > though,
> > > > > reducing their precision. In order to accomodate the new 8K pen
> (and
> > > any
> > > > > future pens with even higher precision), this patch bumps up the
> full-
> > > > > scale range to be 0..65535. This number was chosen both because it
> far
> > > > > exceeds anything currently known about, and also because it
> matches the
> > > > > normalization range used over the wire by the Wayland tablet
> protocol.
> > > > >
> > > > > Note that the WACOM_PROP_PRESSURE_THRESHOLD value has been tied to
> the
> > > > > normalized (2048-level) pressure range for some time, meaning that
> we
> > > > > cannot simply change the range without causing a change in the
> > > perceived
> > > > > threshold for users. To ensure compatibility, the value is
> interpreted
> > > > > as a fraction of 2048 and then scaled to the actual normalization
> > > range.
> > > > >
> > > > > Signed-off-by: Jason Gerecke <jason.gere...@wacom.com
> <javascript:;> <javascript:;>>
> > > >
> > > > Reviewed-by: Ping Cheng <pi...@wacom.com <javascript:;>
> <javascript:;>> for the set of
> > > 2 patches.
> > > >
> > > > Thank you for considering backward compatibility. That's a bonus for
> > > > many system admins who use xsetwacom/xinput to configure the driver.
> > > >
> > > > Please update this patch as Peter suggested though.
> > >
> > > uhm, just something else I noticed. we precalculate the pressure
> curve, so
> > > we now have 256 KB in the driver allocated just for the values. We
> should
> > > probably split this out to be allocated on demand
> >
> >
> > How do you plan to make it on demand? Will it add a new API?
>
> Changing pPressCurve[FILTER_PRESSURE_RES + 1] to a dynamically allocated
> memory should be enough, no new API is needed, this is just an
> implementation detail.
Great! That's smart. Then go for it ;).
Cheers,
Ping
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