Re: [PATCH] HID: input: fix input sysfs path for hid devices

From: Jiri Kosina
Date: Fri Dec 20 2013 - 17:36:27 EST


On Thu, 19 Dec 2013, David Herrmann wrote:

> <benjamin.tissoires@xxxxxxxxxx> wrote:
> > we used to set the parent of the input device as the parent of
> > the hid bus. This was introduced when we created hid as a real bus, and
> > to keep backward compatibility. Now, it's time to proper set the parent
> > so that sysfs has an idea of which input device is attached to
> > which hid device.
> >
> > Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>
> > ---
> >
> > Hi Jiri,
> >
> > well, the regression test did not showed anything bad, and a look at the hid
> > drivers also showed that no drivers should be armed by that.
> >
> > I think this is valuable because it will give a better understanding of the
> > actual mapping hardware/inputs. Like a touchscreen with pen + touch will have
> > the same hid parent, and I expect X/Wayland to be able to detect this at some
> > point to keep the mapping correctly between the two input devices and the screen.
> >
> > I also need that for hid-replay, so that I can be sure which input is attached
> > to which uhid device, and give up the heuristics I currently use.
>
> I was just wondering where we have multiple HID devices on a single
> parent, but yeah, uhid is a good example. I actually have no
> objections to this patch and it looks fine. But I cannot tell whether
> anyone relies on this.
>
> I'd say we should give it a try.

Agreed, let's take it for 3.14, and if anyone complains about breakage
caused by this (which I don't expect), we'll revert to the previous state.

--
Jiri Kosina
SUSE Labs
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