On Wed, Nov 30, 2016 at 8:13 PM, Aniroop Mathur <a.mathur@xxxxxxxxxxx> wrote: > On 30 Nov 2016 19:05, "Lars-Peter Clausen" <lars@xxxxxxxxxx> wrote: > > > > On 11/27/2016 11:51 AM, Jonathan Cameron wrote: > > > On 26/11/16 03:47, Aniroop Mathur wrote: > > >> msleep(1~20) may not do what the caller intends, and will often sleep longer. > > >> (~20 ms actual sleep for any value given in the 1~20ms range) > > >> This is not the desired behaviour for many cases like device resume time, > > >> device suspend time, device enable time, data reading time, etc. > > >> Thus, change msleep to usleep_range for precise wakeups. > > >> > > >> Signed-off-by: Aniroop Mathur <a.mathur@xxxxxxxxxxx> > > > As these need individual review by the various original authors and driver maintainers to > > > establish the intent of the sleep, it would have been better to have done a series of > > > patches (one per driver) with the relevant maintainers cc'd on the ones that they care about. > > > > > > Most of these are ADI parts looked after by Lars though so perhaps wait for his comments > > > before respining. > > > > I agree with what Jonathan said. For most of these extending the maximum > > sleep time a bit further is ok. > > > > Well, its right that sleep a bit further is okay but this patch is not trying > to solve any major bug. This patch is only trying to make the wake up more > precise than before. So like with msleep(1), process could sleep for 20 ms > so this patch only making the making the process to sleep for 1 ms as > mentioned in the parameter. So I think, changing to usleep_range is only > advantageous and does not cause any harm here. > We have also applied the same change in enable/disable/suspend/resume > functions in accel, gyro, mag, etc drivers and found decent results like the > first sesor data is generated much faster than before so response time > increased. This is critical as sensor can run at a rate of 200Hz / 5ms or > even more now a days in new devices. We even applied in probe as doing the > same in many drivers contribute to a little saving overall in kernel boot up. > Also, it is recommended and mentioned in kernel documentation to use > usleep_range for 1-10 ms. > Sources - > https://www.kernel.org/doc/Documentation/timers/timers-howto.txt > https://lkml.org/lkml/2007/8/3/250 > Hello Mr. Jonathan / Mr. Lars / All, Would you kindly update further about this change? > Thanks. > > BR, > Aniroop Mathur -- 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
