On Wed, Mar 18, 2015 at 6:47 PM, Lars-Peter Clausen <lars@xxxxxxxxxx> wrote: > On 03/18/2015 04:04 PM, 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! >> >> >> First notable problem with using configfs with IIO is boot time modules >> loading. >> >> Because, >> >> * configs uses module_init(configfs_init); >> * IIO uses subsys_initcall(iio_init); >> >> it is guaranteed that IIO will be loaded before configfs. Not fun! :) >> >> So for the moment I will not add configfs support directly into >> industrialiio-core but in a separate module. > > > Just fix configfs, that should clearly not be at the module init level. > > But keeping it in a separate module doesn't hurt either way. Looking at drivers/fs all filesystems modules are at module init level. I'll drop an email to fs folks :). What if IIO core should be at module init core? 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
