Hi All, It's very nice of Felipe to make an issue of accelerometers in Linux kernel again. Before further discussions, we'd better see previous threads about accelerometer. http://lkml.org/lkml/2008/5/20/135 http://lkml.org/lkml/2008/12/1/156 -- I have considered how I can add my accelerometer driver into the Linux kernel nicely for a few months. As Trilok said, there are many accelerometer drivers under drivers/hwmon. So I first tried to add my driver as hwmon, but Jean Delvare didn't agree this idea. Please refer to the following URL: http://lists.lm-sensors.org/pipermail/lm-sensors/2009-April/025686.html And from the next URL, Dmitry don't think it is great idea to add accelerometer as Input system. http://lkml.org/lkml/2008/5/27/283 On Sat, May 16, 2009 at 5:02 AM, Felipe Balbi <felipe.balbi@xxxxxxxxx> wrote: > Hi all, > > > On Fri, May 15, 2009 at 09:30:41PM +0200, ext Mohamed Ikbel Boulabiar wrote: >> I am really interested about that. >> >> But I want to know more about the device, its type, name, ... >> The device isn't HID (Human Interface Device) ? If so, we should >> rethink adding such thing but modify/use hid-input instead. >> >> Because, I have an accelerometer phidget device and it is HID. >> Handling should be the same. > > Yeah, let's try to define the best way to expose accelerometers with > linux kernel and avoid a sysfs hell. Better sooner than later. Felipe, Can I ask why did you say "avoid a sysfs hell"?. I have thought Kernel developers prefer sysfs to IOCTL lately. >> On Fri, May 15, 2009 at 7:06 PM, Trilok Soni <soni.trilok@xxxxxxxxx> wrote: >> > Hi Felipe, >> > >> > Adding linux-input and Jonathan, so not deleting any lines from this e-mail. >> > >> > On Fri, May 15, 2009 at 6:46 PM, Felipe Balbi <felipe.balbi@xxxxxxxxx> wrote: >> >> Hi all, >> >> >> >> the following patch is just an idea to see how the community feels about >> >> it. Considering accelerometer devices, you might have different use >> >> cases for it while running different applications. You could be using it >> >> for screen rotation in one case but when opening a game, you could use >> >> it as a game controller by turning the device side-by-side. >> > >> > There was one proposal from Jonathan called Industrial IO patchset >> > which tried to address these sensor devices. Please grep in your >> > linux-kernel archieve. I believe there are accelerometer drivers under >> > drivers/hwmon. > > The problem is that it doesn't really seem to me that all accelerometers > will be doing hw monitoring. The ones used in laptops, for sure, trying > to prevent the hd from drying during a fall. But imagine the > accelerometers used in, say, wii-mote, or cellphones, or such stuff ? > > Say we wanna use the accelerometer for both screen rotation and gaming, > that device isn't doing hw monitoring and still we _do_ want to set > different thresholds and irq requests/types for different use cases, > right ? Yes, I agree that accelerometer needs new interface. However setting parameters of accelerometer is very different from devices and device specific. Until now, I met two accelerometer, SMB380 from bosch-sensortec and KXSD9 from Kionix. As far as I know, these two accelerometers are quite different from each other and existing accelerometer drivers located /driver/hwmon/ in current Linux kernel. Thus I think sysfs interface (including hwmon-sysfs) is the best solution for setting various parameters of accelerometer.. On the other hand, accelerometers are mostly used as Input device in these days. Most APIs(input_allocate_device, input_allocate_polled_device, ...) and macros(ABS_X, ABS_Y, ...)of Input subsystem are useful to accelerometer too. If we create another APIs and Macros for accelerometers, I think It's another duplicate work and result. It seems like Dmitry concerns input_dev becomes too big with hundreds of sensors.(right?) However, Market trend makes us consider accelerometer as an input device now. I'm sure there is a good way to add accelerometer input system without enlarging input_dev much. In conclusion, We need the inheritance concept in the object-oriented programming. Accelerometer device sometimes can be hwmon device, sometimes input device. So let accelerometer drivers use both APIs of hwmon and input subsystems(hwmon_device_register, input_register_device, input_register_polled_device). Acutally this is what many accelerometer drivers in current Linux kernel are doing, so we don't have to do much. Let's 1) Introduce a new maintainer of accelerometer (Felipe?). 2) Move accelerometer drivers in current Linux kernel to /driver/accelerometer. 3) If we find the common functions of accelerometer or have idea about new API or Macro, let's make at driver/accelerometer/acccelerometer.c, input/linux/acccelerometer.h file or modify input.h little. 4) Add every new accelerometer into /driver/accelerometer. Kyuwon (규원) -- 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
