On Mon, Aug 28, 2017 at 03:02:16PM -0700, Roderick Colenbrander wrote: > On Mon, Aug 28, 2017 at 2:38 PM, Dmitry Torokhov > <dmitry.torokhov@xxxxxxxxx> wrote: > > 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 > > > Thanks for getting back so quickly. The input_dev has all the > information as you could do something with product / vendor ids, which > I wanted to avoid as there are 5 DS4 ids I need to handle and 2 DS3 > ids. We still want to expose the 'gamepad' subdevice, but not the > motion device (INPUT_PROP_ACCELEROMETER), so it would be quite some > logic. Overall I thought it would be cleaner to not have this device > knowledge in joydev and maybe expose a new flag. I believe conceptually this would be wrong, as it would push the knowledge of existing interfaces into the drivers. So just use input ID (and I guess you need to parse phys a bit to see which device you want to handle and which to ignore). 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
