On Mon, Aug 28, 2017 at 02:35:15PM -0700, Roderick Colenbrander wrote: > On Mon, Aug 28, 2017 at 2:16 PM, Dmitry Torokhov > <dmitry.torokhov@xxxxxxxxx> wrote: > > Hi, > > > > On Mon, Aug 28, 2017 at 02:08:54PM -0700, Roderick Colenbrander wrote: > >> On Fri, Aug 25, 2017 at 1:45 AM, Bastien Nocera <hadess@xxxxxxxxxx> wrote: > >> > On Thu, 2017-08-24 at 16:11 -0700, Roderick Colenbrander wrote: > >> >> From: Roderick Colenbrander <roderick.colenbrander@xxxxxxxx> > >> >> > >> >> This new property can be set on input devices to blacklist them > >> >> from getting picked up by joydev. This is meant for devices, which > >> >> pass joydev its heuristics, but for which there is no good generic > >> >> way of updating the heuristics. > >> > > >> > I can't make sense of that last sentence, and the possessive for > >> > "heuristics" (here and below in the documentation) is, IMO, > >> > unnecessary. > >> > > >> >> Signed-off-by: Roderick Colenbrander <roderick.colenbrander@xxxxxxxx> > >> >> --- > >> >> Documentation/input/event-codes.rst | 9 +++++++++ > >> >> include/uapi/linux/input-event-codes.h | 1 + > >> >> 2 files changed, 10 insertions(+) > >> >> > >> >> diff --git a/Documentation/input/event-codes.rst > >> >> b/Documentation/input/event-codes.rst > >> >> index a8c0873..ae8c546 100644 > >> >> --- a/Documentation/input/event-codes.rst > >> >> +++ b/Documentation/input/event-codes.rst > >> >> @@ -356,6 +356,15 @@ can report through the rotational axes (absolute > >> >> and/or relative rx, ry, rz). > >> >> All other axes retain their meaning. A device must not mix > >> >> regular directional axes and accelerometer axes on the same event > >> >> node. > >> >> > >> >> +INPUT_PROP_JOYDEV_IGNORE > >> >> +------------------------ > >> >> + > >> >> +The joydev interface uses heuristics to determine whether it should > >> >> expose an > >> >> +input device through joydev. Some devices pass its heuristics, but > >> >> don't > >> >> +make sense to expose. In some cases the generic heuristics can be > >> >> updated, > >> >> +but in other cases this is not easy. The INPUT_PROP_JOYDEV_IGNORE > >> >> flag can > >> >> +be set by drivers to explicit request blacklisting by joydev. > >> > > >> > The "don't make sense to expose" is not what we're trying to do here > >> > though. The problem is rather that "we used not to show this device > >> > through joydev, but programs using joydev are limited and usually not > >> > updated so we should only show what we used to". > >> > > >> > >> Thanks, I will change the wording. Originally I wrote it like this, > >> because I thought joydev applications could not determine at all which > >> axes were being used except for 'an axis number' and for that reason > >> thought that the match function had some heuristics (e.g. filtering > >> out touchpad devices and others), making sure a joystick has buttons > >> etcetera. I wasn't aware of JSIOCGAXMAP, which does allow applications > >> to get more information about a device, but you can't easily determine > >> if something is e.g. a motion sensor device you would need to do a > >> string compare on known strings or make assumptions if you see a > >> device with axes, but no buttons. > > > > Sorry for the delay, but exposing the internal kernel decisions to > > userspace is not something that we need to do. Why would userspace care > > to see this in device properties? > > > > Also, this whole thing puts knowledge of interfaces into the drivers, > > and driver should not care at all what interfaces kernel might > > implement. Do drivers need to be aware that there is SysRq handler? Or > > that on some versions of ChromeOS there is a handler that bumps up > > CPU frequency in response to user activity? > > > > If you really want to stop joydev from attaching to some devices then > > the decision should go in joydev itself, not spread across multiple > > drivers. > > > > Thanks. > > > > -- > > Dmitry > > Correct user space should not have to be aware. Originally the patch > add a composite device flag, but that term was more loaded and needed > ioctls. That field would have made sense for user space, but this flag > not, we just piggy-backed on the the properties field in the > input_dev. > > In my case of ds3/ds4 to fix old applications, I want to blacklist > joydev in some way, but joydev doesn't have access to enough > information except for INPUT_PROP_ACCELEROMETER which I think you felt > was not narrow enough in scope. > > Would the solution be to add some new private quirks/flags field to > 'struct input_dev', which joydev could use? Or is there another > solution you have in mind. What kind of data joydev is missing? There is the input_id with bus, vendor, product and version, device capabilities, plus you have full access to the input device itself, so you can look up name, phys, etc. Thanks. -- Dmitry -- 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
