On Sun, Dec 18, 2016 at 09:35:48AM +0200, Igor Grinberg wrote:

Hi Aniroop Mathur,


On 12/04/16 15:05, Aniroop Mathur wrote:

quoted

Hello Mr. Igor Grinberg

On Sun, Dec 4, 2016 at 1:32 PM, Igor Grinberg [off-list ref] wrote:

quoted

Hi Aniroop Mathur,

On 11/29/16 23:02, Aniroop Mathur wrote:

quoted

Dear Mike Rapoport, Igor Grinberg,
Greetings!

I am Aniroop Mathur from Samsung R&D Institute, India.

I have submitted one patch as below for review to Linux Open Source.
The problem is that we do not have the hardware available with us to
test it and we would like to test it before actually applying it.
As you are the author of this driver, I am contacting you to request you
provide your feedback upon this patch.

Also if you have the hardware available, could you please help to
test this patch on your hardware? or could you provide contact points
of individuals who could support to test it?

This touchpad and the driver was used on an old PXA270 based PDA.
I currently don't have those at hand to test the patch.

quoted

Thank you!

BR,
Aniroop Mathur

On Tue, Nov 29, 2016 at 1:25 AM, Aniroop Mathur [off-list ref] wrote:

quoted

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)

Well, it should be at least 1ms as stated in my comment just before the define.
So, from the correctness perspective larger values will also do the job.
Additionally, since I've taken a spare 2ms, and you are making it even more
precise (3000us + 100us) - it will still do the job and stay correct.
So, there should be no issue from correctness POV.

Alright, Thanks!

quoted

quoted

quoted

This is not the desired behaviour for many cases like device resume time,
device suspend time, device enable time, retry logic, etc.
Thus, change msleep to usleep_range for precise wakeups.

This is a human interface touchpad device, even having 20ms soft reset
sleep time will not impact the responsiveness for humans.
IMHO, there is no need for precise wakeups for this device, so I wouldn't
bother.

Well, from the point of view of device working and responsiveness for "humans",
I agree that it is okay to sleep for 20 / 40 ms or even 100 ms. However, this
patch is not trying to solve any such issues. This patch is only trying to make
the process sleep for appropriate time as mentioned in the parameter and does
not cause any harm here. I could see that this function is called during device
resume and device probe time. So this change will improve the resume and probe
time for this device and doing the same change in other drivers will
contribute to
improvement in overall kernel resume and boot time a little bit so response time
increases a little bit. Plus, it is recommended and mentioned in kernel
documentation to use usleep_range for delays between 1-10 ms.
So usleep_range should serve better here.
Explained originally here to why not use msleep for 1 - 20 ms:
http://lkml.org/lkml/2007/8/3/250

I have absolutely 0 objections to this.
So, as I already have said, it will be hard for me to test it currently, but
if you want it and Dmitry wants to apply it, my ack is below.

OK, it does not matter much either way, but let's apply it.

quoted

quoted

quoted

quoted

Signed-off-by: Aniroop Mathur <redacted>

Acked-by: Igor Grinberg <redacted>

Thanks.

-- 
Dmitry