linux-kernel - Re: [PATCH] iio: srf04: fix wrong limitation in distance measuring

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Date:   Mon, 9 Sep 2019 15:00:22 +0200
From:   Andreas Klinger <ak@...klinger.de>
To:     Zbyněk Kocur <zbynek.kocur@....cvut.cz>
Cc:     Jonathan Cameron <jic23@...nel.org>, linux-iio@...r.kernel.org,
        knaack.h@....de, lars@...afoo.de, pmeerw@...erw.net,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iio: srf04: fix wrong limitation in distance measuring

Hi Zbyněk,

thanks a lot for testing and sharing your results with us.

> I do not know how to do this in the development of drivers, whether it makes
> sense to put a filter directly into the driver or at least pull the maximum
> distance parameter as a variable?

In this case one should read several times, remove spikes and calculate the
average. This sounds to me as task for the userspace not for the driver.

Regards,

Andreas


Zbyněk Kocur <zbynek.kocur@....cvut.cz> schrieb am Mo, 09. Sep 08:53:
> Hi Andreas,
> 
> I'm so sorry for the delay. I was working on another project now, and I wasn't entirely devoted to this. I looked at it at the weekend and the modified code is working. I have only tested OpenWRT in build - r10204-38b22b1, kernel 4.14.125. I do not expect complications on other platforms.
> 
> I tried it on several sensors. I was primarily interested in JSN-SR04T (https://www.makerguides.com/jsn-sr04t-arduino-tutorial/). I have also verified other designs (https://randomnerdtutorials.com/complete-guide-for-ultrasonic-sensor-hc-sr04/).
> 
> It generally works. Relatively accurate for the area up to 2.5 m. However, if the distance is longer, it starts to fizz, depending on the sensor design. It is a property of used HW and its construction.
> 
> I do not know how to do this in the development of drivers, whether it makes sense to put a filter directly into the driver or at least pull the maximum distance parameter as a variable?
> 
> Anyway, the change made works.
> 
> Zbynek
> ---
> email: zbynek.kocur@....cvut.cz
> phone: +420 224 354 054
> web: http://www.fel.cvut.cz
> Department of Telecommunications Engineering
> Faculty of Electrical Engineering
> 
> > On 7 Sep 2019, at 11:46, Andreas Klinger <ak@...klinger.de> wrote:
> > 
> > Hi Zbynek,
> > 
> > do you have any feedback for us?
> > 
> > Thank you,
> > 
> > Andreas
> > 
> > 
> > Zbyněk Kocur <zbynek.kocur@....cvut.cz> schrieb am Mi, 26. Jun 21:50:
> >> Thank you, i will write a feedback after testing.
> >> 
> >> 
> >> Zbynek
> >> ---
> >> email: zbynek.kocur@....cvut.cz
> >> phone: +420 224 354 054
> >> web: http://www.fel.cvut.cz
> >> Department of Telecommunications Engineering
> >> Faculty of Electrical Engineering
> >> 
> >>> On 26 Jun 2019, at 21:49, Jonathan Cameron <jic23@...nel.org> wrote:
> >>> 
> >>> No rush, it's a clear fix anyway so we can queue this up
> >>> in the rc phase of the next kernel cycle!
> >> 
> > 
> > -- 
> > Andreas Klinger
> > Grabenreith 27
> > 84508 Burgkirchen
> > +49 8623 919966
> > ak@...klinger.de
> > www.it-klinger.de
> > www.grabenreith.de
> 



-- 
Andreas Klinger
Grabenreith 27
84508 Burgkirchen
+49 8623 919966
ak@...klinger.de
www.it-klinger.de
www.grabenreith.de