On 2014-03-26 08:08, Antti Seppälä wrote:
On 26 March 2014 01:21, David Härdeman <david@xxxxxxxxxxx> wrote:
On Tue, Mar 25, 2014 at 09:12:11AM +0000, James Hogan wrote:
On Tuesday 25 March 2014 00:51:46 David Härdeman wrote:
What's the purpose of providing the sw scancode filtering in the
case where
there's no hardware filtering support at all?
Consistency is probably the main reason, but I'll admit it's not
perfectly
consistent between generic/hardware filtering (mostly thanks to NEC
scancode
complexities), and I have no particular objection to dropping it if
that isn't
considered a good enough reason.
I'm kind of sceptical...and given how difficult it is to remove
functionality that is in a released kernel...I think that particular
part (i.e. the software filtering) should be removed until it has had
further discussion...
...
I don't understand. What's the purpose of a "software fallback" for
scancode filtering? Antti?
Well since the ImgTec patches will create a new sysfs interface for
the HW scancode filtering I figured that it would be nice for it to
also function on devices which lack the hardware filtering
capabilities. Especially since it's only three lines of code. :)
Therefore I suggested the software fallback. At the time I had no clue
that there might be added complexities with nec scancodes.
It's not only NEC scancodes, the sw scancode filter is state that is
changeable from user-space and which will require reader/writer
synchronization during the RX path (which is the "hottest" path in
rc-core). I've posted patches before which make the RX path lockless,
this change makes complicates such changes.
Additionally, the provision of the sw fallback means that userspace has
no idea if there is an actual hardware filter present or not, meaning
that a userspace program that is aware of the scancode filter will
always enable it.
So, I still think the SW part should be reverted, at least for now (i.e.
the sysfs file should only be present if there is hardware support).
Mauro?
//David
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