On 15/02/16 09:42, Gregor Boirie wrote: > On 02/14/2016 06:43 PM, Lars-Peter Clausen wrote: >> On 02/13/2016 03:14 PM, Jonathan Cameron wrote: >>> On 11/02/16 10:04, Gregor Boirie wrote: >>>> diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio >>>> index 3c66248..4602006 100644 >>>> --- a/Documentation/ABI/testing/sysfs-bus-iio >>>> +++ b/Documentation/ABI/testing/sysfs-bus-iio >>>> @@ -32,6 +32,13 @@ Description: >>>> Description of the physical chip / device for device X. >>>> Typically a part number. >>>> +What: /sys/bus/iio/devices/iio:deviceX/clockid >>>> +KernelVersion: 4.5 >>>> +Contact: linux-iio@xxxxxxxxxxxxxxx >>>> +Description: >>>> + Identifier (clockid_t) of current posix clock used to timestamp >>>> + buffered samples and events for device X. >>> As it's been written into a sysfs attribute I'd normally prefer to see a >>> descriptive string for something like this. What do others think? >>> clockid_t is clearly fixed abi so this makes reasonable sense. Are there >>> other sysfs attributes to select the clock already present elsewhere in the >>> kernel? >> Very same thoughts here. clockid_t is already ABI so we don't have to be >> afraid exposing values that might change, but at the same time a string >> would be more suitable for sysfs. > I was driven by simple userspace implementation at the cost of sysfs conventions. > Moreover, no kernel side parsing is needed in this way. > Using a stringifi'ed clockid_t allows trivial clock selection with following libiio based > code snippet: > </code> > int err; > ... > err = iio_device_attr_write(indio_dev, "clockid", STRINGIFY(CLOCK_MONOTONIC)); > if (err < 0) > goto error; > <code/> > > And even simpler retrieval and use of current clock: > </code> > int err; > long long clockid; > struct timespec tspec; > ... > err = iio_device_attr_read_longlong(indio_dev, "clockid", &clockid); > if (err < 0) > goto error; > ... > clock_gettime((clockid_t) clockid, &tspec); > ... > <code/> > > Implementing this with a descriptive string is no big deal anyway. I can modify this > part if you feel sysfs conventions respect prevails. Sorry to be a pain, but I think that it is worth the somewhat silly jumping through hoops to sysfsify it. Keeping sysfs as 'self documenting' as possible is always a good aim. Thanks, Jonathan > > gregor. > -- > 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
