On Thu, Dec 09, 2010 at 02:01:59PM -0800, Ping Cheng wrote:
> On Thu, Dec 9, 2010 at 1:30 PM, Chris Bagwell <[email protected]> wrote:
> >> Event if we set absinfo.resolution properly in the kernel driver, we
> >> can not pass them to the user land. There is no ioctl to support it
> >> yet. I have raised this question last month. No one followed that RFC.
> >
> > Maybe I missed that part of your emails. Resolution is returned as
> > apart of EVIOCGABS that we are querying today. Its returning zero
> > today I guess.
>
> The EVIOCGABS ioctl does not report resolution since the corresponding
> kernel function: input_set_abs_params() does not have a room for
> resolution. My email to linux-input is attached below for your
> reference.
Have a look at the drivers/input/mouse/synaptics.
commit ec20a022aa24fc63d3ab59584cb1e5aa9a21d46c
Refs: v2.6.30-36-gec20a02
Input: synaptics - add support for reporting x/y resolution
the driver currently uses input_abs_set_res(), added in
commit 987a6c0298260b7aa40702b349282554d6180e4b
Refs: v2.6.35-rc3-59-g987a6c0
Input: switch to input_abs_*() access functions
synaptics and evdev both get the resolution from the kernel, if the
respective kernel driver sets it.
Cheers,
Peter
> On Sun, Nov 14, 2010 at 12:40 PM, Ping Cheng <[email protected]> wrote:
> > I have thought about the resolution issue for a while. I didn't want
> > to tocuh it since it affects all HID drivers. Resolution has been
> > added to absinfo since kernel 2.6.31. But no kernel driver has passed
> > resolution to the userland yet. We (linuxwacom project) still keep a
> > resolution table in the X driver. Passing resolution to the userland
> > from the kernel can get rid of those tables and avoid retrieving that
> > information from HID descriptor.
> >
> > One simple way to support resolution is to add "int res" to
> > input_set_abs_params(...). This means an interface change. All HID
> > drivers that call input_set_abs_params() have to be updated. We could
> > introduce a new input_set_abs_something so only those drivers that
> > want to pass the resolution switch to the new routine. Maybe you guys
> > have other suggestions?
> >
> > Ping
> >
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