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. Thanks, Roderick -- 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
