Hi Aniroop Mathur, On 12/04/16 15:05, Aniroop Mathur wrote: > Hello Mr. Igor Grinberg > > On Sun, Dec 4, 2016 at 1:32 PM, Igor Grinberg <grinberg@xxxxxxxxxxxxxx> wrote: >> Hi Aniroop Mathur, >> >> On 11/29/16 23:02, Aniroop Mathur wrote: >>> 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. >> >>> >>> Thank you! >>> >>> BR, >>> Aniroop Mathur >>> >>> On Tue, Nov 29, 2016 at 1:25 AM, Aniroop Mathur <a.mathur@xxxxxxxxxxx> 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) >> >> 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! > >>>> 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. >>>> >>>> Signed-off-by: Aniroop Mathur <a.mathur@xxxxxxxxxxx> Acked-by: Igor Grinberg <grinberg@xxxxxxxxxxxxxx> >>>> --- >>>> drivers/input/mouse/synaptics_i2c.c | 4 ++-- >>>> 1 file changed, 2 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/drivers/input/mouse/synaptics_i2c.c b/drivers/input/mouse/synaptics_i2c.c >>>> index aa7c5da..4d688a6 100644 >>>> --- a/drivers/input/mouse/synaptics_i2c.c >>>> +++ b/drivers/input/mouse/synaptics_i2c.c >>>> @@ -29,7 +29,7 @@ >>>> * after soft reset, we should wait for 1 ms >>>> * before the device becomes operational >>>> */ >>>> -#define SOFT_RESET_DELAY_MS 3 >>>> +#define SOFT_RESET_DELAY_US 3000 >>>> /* and after hard reset, we should wait for max 500ms */ >>>> #define HARD_RESET_DELAY_MS 500 >>>> >>>> @@ -311,7 +311,7 @@ static int synaptics_i2c_reset_config(struct i2c_client *client) >>>> if (ret) { >>>> dev_err(&client->dev, "Unable to reset device\n"); >>>> } else { >>>> - msleep(SOFT_RESET_DELAY_MS); >>>> + usleep_range(SOFT_RESET_DELAY_US, SOFT_RESET_DELAY_US + 100); >>>> ret = synaptics_i2c_config(client); >>>> if (ret) >>>> dev_err(&client->dev, "Unable to config device\n"); >>>> -- >>>> 2.6.2 >>>> >>> >> >> -- >> Regards, >> Igor. > -- Regards, Igor. -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
