On Sat, Dec 3, 2016 at 2:30 PM, Jonathan Cameron <ji...@kernel.org> wrote: > On 02/12/16 19:07, Aniroop Mathur wrote: >> On Wed, Nov 30, 2016 at 8:13 PM, Aniroop Mathur <a.mat...@samsung.com> wrote: >>> On 30 Nov 2016 19:05, "Lars-Peter Clausen" <l...@metafoo.de> 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.mat...@samsung.com> >>> > > 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? > Hi Aniroop, > > Quite a few of us only manage to get to kernel patches once or twice a week > (in my case only on weekends most weeks). > > Anyhow, I've applied this patch as is. I don't necessarily think the change > is that important in the probe paths, but as you said it does little harm. > > So what the heck ;) > > Applied to the togreg branch of iio.git which I'll push out as testing > once I have a net connection (currently on a train). >
This sounds great !! Thanks a lot :) BR, Aniroop Mathur > Thanks, > > Jonathan >> >> >>> Thanks. >>> >>> BR, >>> Aniroop Mathur >
