On Mon, Sep 08, 2014 at 06:35:53PM -0700, Greg Kroah-Hartman wrote: > On Mon, Sep 08, 2014 at 05:04:30PM -0700, Darren Hart wrote: > > On Fri, Sep 05, 2014 at 11:04:18PM -0600, Azael Avalos wrote: > > > Hi there, > > > > > > 2014-09-05 20:42 GMT-06:00 Darren Hart <dvhart@xxxxxxxxxxxxx>: > > > > On Fri, Sep 05, 2014 at 11:14:05AM -0600, Azael Avalos wrote: > > > >> The accelerometer sensor is very sensitive, and having userspace > > > >> poll the sysfs position entry is not very battery friendly. > > > >> > > > >> This patch removes the sysfs entry and instead, it creates an > > > >> input polled device (joystick) for the built-in accelerometer. > > > > > > > > Hrm, while sysfs details can change across kernel versions, usually due to > > > > driver core changes, we try to keep them as consistent as possible so as not to > > > > break userspace. > > > > > > > > That said, if we are going to try and come up with a better model for > > > > representing an accelerometer, wouldn't treating it as an IIO device be the more > > > > logical approach? > > > > > > Yes of course, but the actual accelerometer device (sensor?) is not > > > really exposed, > > > only certain "functions" it provides, and they are divided across two > > > different ACPI devices, > > > TOS620A exposes the protection, and the TOS1900 (and et. al.) only > > > exposes the axes. > > > > As I understand it, IIO defines an interface to a device, a standard sysfs set > > of properties. I should think we could provide the appropriate callbacks even > > for a partially implemented (or a pair of) accelerometer. > > > > Jonathan, what are your thoughts here. Is such a "device" (ACPI accessors to > > axis and threshold) a candidate for IIO, or is this input polled device more > > appropriate? > > > > > > > > I see your point in breaking userspace, but given the fact that it was > > > recently introduced, > > > I didn't thought it was already "adopted", that's why I decided to > > > remove the sysfs entry. > > > > Looks like since 3.15 if I read the log correctly. That is fairly recent and > > this is not one of the "defined interfaces" in the sysfs documentation. > > > > Greg, can you weigh in here - does this change count as "breaking userspace", or > > is this more inline with the scheduler knobs in /proc/sched_debug which can > > change from version to version. > > > > > > > > Then we might as well keep the sysfs entry and have the input polled > > > device as well. > > > > Let's see what Greg has to say. If he isn't bothered by the change, I won't push > > the issue. > > If it should be an IIO device, great, make it an IIO device, and move > away from a custom sysfs interface that matches nothing else. > > But I really doubt it should be a joystick device, that just doesn't > make sense at all. I immediately went to a tablet with a marble maze game and it didn't seem too crazy, but I don't suppose that is what people are actually doing with it... What are people actually doing with this thing Azael? -- Darren Hart Intel Open Source Technology Center -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
