On 15/03/15 20:34, Daniel Baluta wrote: > On Sat, Mar 14, 2015 at 7:21 PM, Jonathan Cameron <jic23@xxxxxxxxxx> wrote: >> On 12/03/15 12:48, Daniel Baluta wrote: >>> On Thu, Mar 12, 2015 at 10:40 AM, Lars-Peter Clausen <lars@xxxxxxxxxx> wrote: >>>> On 03/12/2015 09:16 AM, Octavian Purdila wrote: >>>>> >>>>> On Wed, Mar 11, 2015 at 6:36 PM, Daniel Baluta <daniel.baluta@xxxxxxxxx> >>>>> wrote: >>>>>> >>>>>> >>>>>> As written in Documentation/ABI/testing/sysfs-bus-iio the trigger >>>>>> attribute for sampling frequency should be sampling_frequency. >>>>>> >>>>>> Fix this for iio-trig-periodic-rtc module in order to prepare it >>>>>> for moving out of staging. >>>>>> >>>>>> Signed-off-by: Daniel Baluta <daniel.baluta@xxxxxxxxx> >>>>>> --- >>>>>> Jonathan, this module is very useful for devices that do not have >>>>>> an interrupt pin. >>>>>> >>>>>> We are working on drivers for such devices and would be very nice to >>>>>> move this driver in advance to the IIO non-staging location. >>>>>> >>>>>> What do you say? >>>>>> >>>>> >>>>> Hmm, I wonder what are the advantages of using RTC timers. Couldn't we >>>>> use a regular kernel timer instead? >>>> >>>> >>>> The long term plan is to get rid of the RTC timer trigger due to its various >>>> limitations (poor resolution, etc). >>>> >>>> There is the hrtimer trigger >>>> (https://github.com/analogdevicesinc/linux/blob/xcomm_zynq/drivers/staging/iio/trigger/iio-trig-hrtimer.c) >>>> but we haven't agreed on a proper interface yet how to instantiate the >>>> hrtimer trigger. >>>> >>>> Check the ml archive for the various discussions on it: >>>> http://marc.info/?l=linux-iio&w=2&r=1&s=hrtimer&q=b >>> >>> >>> Hi Lars, >>> >>> That was an interesting reading. There were people trying to push >>> hrtimer based IIO trigger 4 years ago :). >>> >>> I think it's now the time to have this upstream. >>> >>> I will be back :) (as many others said before) with an RFC patch. >>> >>> I think we should keep the following requirements: >>> >>> 1) Create a common framework for software based triggers. >>> 2) User space driven configuration for trigger instances, >>> as opposed to platform device files used for RTC based trigger >>> 3) Remove RTC interrupt source, use hrtimers instead >>> >>> Still not clear, but I will trying to figure it out during implementation: >>> >>> 4) configfs vs sysfs interface. >>> >>> At the first glance, I would say we should stay with sysfs interface in order >>> to avoid another dependency. But let's see how it works. >> This issue with the sysfs only approach (as originally raised by Lars) >> is that it is actually very poorly suited to instantiating new elements of >> the device model. Configfs was introduced in the first place exactly to >> cover this area. We only ended up with the instantiation code in >> the sysfs trigger via sysfs because at the time (a good long while ago!) >> I wasn't aware of configfs. >> >> I have some initial work on the base elements on an iio configfs interface >> somewhere that I can dig out if you like. I started working on it in a rare >> quiet period about a year ago, but never got all that far. >> >> There aren't that many examples in tree of how to actually use configfs >> so it's a bit more of a learning curve than sysfs! > > I use this: > > http://lxr.free-electrons.com/source/Documentation/filesystems/configfs/configfs_example_explicit.c > > as an example. But, sure if you find your work please share. Hmm I think the branch I just pushed to iio.git as configfstest might be the last code I had. Not sure I got much beyond trying to create the infrastructure for the subsystem to have quite a few different things under a semi unified location in configfs. Honestly can't really recall what this actually does! Jonathan > > I am not sure if we could use this approach for iio-trig-interrupt trigger? > > Daniel. > -- > 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 > -- 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
