Re: ti_am33x_adc sampling bugs

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



I'm not quite aware of what's in mainline or not, this list was CC'd by Zubair Lutfullah who authored the patches in question. Hopefully he can provide more insight or a possible fix.

0019-iio-ti_am335x_adc-Add-continuous-sampling-and-trigge.patch
Subject: [PATCH 19/21] iio: ti_am335x_adc: Add continuous sampling and
 trigger support

Previously the driver had only one-shot reading functionality.
This patch adds triggered buffer support to the driver.
A buffer of samples can now be read via /dev/iio.


On 3/31/2014 4:59 PM, Jonathan Cameron wrote:


On March 31, 2014 5:47:54 PM GMT+01:00, Rob Mosher <nyt@xxxxxxxxxxxxxxxxxxx> wrote:
I believe the AIN files came from
0020-iio-ti_am335x_adc-Add-IIO-map-interface.patch.

Ouch that is an 'unusual' patch... No more recent patches in mainline appear related to what you are seeing unfortunately.



The bug is the
same
reading from in_voltageX_raw files.

On 3/31/2014 12:14 PM, Jonathan Cameron wrote:


On March 31, 2014 9:17:53 AM GMT+01:00, Rob Mosher
<nyt@xxxxxxxxxxxxxxxxxxx> wrote:
The following patches were removed and behavior returned to normal.

0019-iio-ti_am335x_adc-Add-continuous-sampling-and-trigge.patch
0020-iio-ti_am335x_adc-Add-IIO-map-interface.patch

Once 19 was re-applied, the bug returned.

It would appear that patch19 is the problem.  On an unrelated note,
the

continuous sampling patch seems to still be missing the mode file to
tell it to sample continuously or oneshot in the sysfs directory as
referenced at
http://processors.wiki.ti.com/index.php/AM335x_ADC_Driver%27s_Guide.
Someone should update that wiki page.
Such an attribute was not and will not be
   part of the mainline kernel ABI. Drivers can play fast and loose in
staging but to move
   out the ABI must conform to existing definitions or be proposed
reviewed and accepted.

I am somewhat confused. Where did the AIN sysfs attributes come from?

Maybe this should be moved to the beta kernel until stable?


Cheers.

On 3/31/2014 12:04 AM, Rob Mosher wrote:
(sorry for the duplicate, got bounces due to HTML encoding)

The specified patch is already included.  The system was running
the
latest kernel from Robert Nelson's repo.  Any suggestions?  I'll
try
removing some of the patches to see if it fixes this behavior.  I
have a
feeling I know which one is doing it.

Thanks.

output from running patch.sh with source pulled from
https://github.com/beagleboard/kernel/tree/3.8



/home/bbuild/comp/kernel/patches/adc/0017-IIO-ADC-ti_adc-Fix-1st-sample-read.patch:
applied

Just in case, I built and installed the kernel and the same
behavior
persisted.

root@rbone:/# uname -a
Linux rbone 3.8.13-00737-g7dfad77 #1 SMP Sun Mar 30 22:11:44 EDT
2014
armv7l GNU/Linux

gpio30 is connected to AIN4 using a voltage divider

root@rbone:/# cd /sys/class/gpio/
root@rbone:/sys/class/gpio# echo 30 > export
root@rbone:/sys/class/gpio# echo BB-ADC >
/sys/devices/bone_capemgr.9/slots
root@rbone:/sys/class/gpio# cd /sys/devices/ocp.3/helper.11/
root@rbone:/sys/devices/ocp.3/helper.11# echo out >
/sys/class/gpio/gpio30/direction

root@rbone:/sys/devices/ocp.3/helper.11# echo 1 >
/sys/class/gpio/gpio30/value
root@rbone:/sys/devices/ocp.3/helper.11# cat AIN4
1460

root@rbone:/sys/devices/ocp.3/helper.11# echo 0 >
/sys/class/gpio/gpio30/value
root@rbone:/sys/devices/ocp.3/helper.11# cat AIN4
0

root@rbone:/sys/devices/ocp.3/helper.11# grep . AIN[0-3] AIN[5-7]
AIN0:1550
AIN1:1213
AIN2:1485
AIN3:795
AIN5:513
AIN6:744
AIN7:1698

root@rbone:/sys/devices/ocp.3/helper.11# echo 1 >
/sys/class/gpio/gpio30/value
root@rbone:/sys/devices/ocp.3/helper.11# cat AIN4
0
root@rbone:/sys/devices/ocp.3/helper.11# cat AIN4
0
root@rbone:/sys/devices/ocp.3/helper.11# cat AIN4
0
root@rbone:/sys/devices/ocp.3/helper.11# cat AIN4
0
root@rbone:/sys/devices/ocp.3/helper.11# cat AIN4
0
root@rbone:/sys/devices/ocp.3/helper.11# cat AIN4
0
root@rbone:/sys/devices/ocp.3/helper.11# cat AIN4
1460

On 3/30/2014 9:16 AM, Zubair Lutfullah wrote:


https://github.com/beagleboard/kernel/blob/3.8/patches/adc/0017-IIO-ADC-ti_adc-Fix-1st-sample-read.patch

IIRC, this patch fixes this issue

Can you compile the kernel from the sources and check?
https://github.com/beagleboard/kernel/tree/3.8

Regards
ZubairLK

On Sun, Mar 30, 2014 at 7:04 AM, Rob Mosher
<nyt@xxxxxxxxxxxxxxxxxxx
<mailto:nyt@xxxxxxxxxxxxxxxxxxx>> wrote:

      Just a note, the same behavior persists with BB-ADC dtb and
      reading from in_voltage4_raw


      On 3/30/2014 12:30 AM, Rob Mosher wrote:

          Hello fine developers,

          It seems I've stumbled upon a problem while developing a
full
          featured Ruby gem for the Beaglebone.

          It seems a patch included in the beaglebone kernel causes
some
          issues while reading analog inputs.  Apparently the
samples
          get backlogged by the number of adc pins in use.  I'm not
sure
          which patch exactly as there are a number that affect adc
          buffering and I'm not currently setup for kernel
building,
          however the below output should detail the problem.

          Using the official Debian image.
          Linux rbone 3.8.13-bone43 #1 SMP Wed Mar 26 14:21:39 UTC
2014
          armv7l GNU/Linux

          Distributor ID: Debian
          Description:    Debian GNU/Linux 7.4 (wheezy)
          Release:        7.4
          Codename:       wheezy

          root@rbone:~# echo cape-bone-iio >
          /sys/devices/bone_capemgr.9/slots

          This is the normal and expected behavior.

          1.8v applied to AIN4
          root@rbone:/sys/devices/ocp.3/helper.12# cat AIN4
          1798

          0v applied to AIN4
          root@rbone:/sys/devices/ocp.3/helper.12# cat AIN4
          0

          1.8v applied to AIN4
          root@rbone:/sys/devices/ocp.3/helper.12# cat AIN4
          1798

          0v applied to AIN4
          root@rbone:/sys/devices/ocp.3/helper.12# cat AIN4
          0

          So far working as intended....  Now reading from the
other
pins.

          root@rbone:/sys/devices/ocp.3/helper.12# grep . AIN[0-3]
AIN[5-7]
          AIN0:1563
          AIN1:1221
          AIN2:1487
          AIN3:789
          AIN5:514
          AIN6:743
          AIN7:1698

          Now applying 1.8v to AIN4
          root@rbone:/sys/devices/ocp.3/helper.12# cat AIN4
          0
          root@rbone:/sys/devices/ocp.3/helper.12# cat AIN4
          0
          root@rbone:/sys/devices/ocp.3/helper.12# cat AIN4
          0
          root@rbone:/sys/devices/ocp.3/helper.12# cat AIN4
          0
          root@rbone:/sys/devices/ocp.3/helper.12# cat AIN4
          0
          root@rbone:/sys/devices/ocp.3/helper.12# cat AIN4
          0
          root@rbone:/sys/devices/ocp.3/helper.12# cat AIN4
          1798

          Now applying 0v to AIN4

          root@rbone:/sys/devices/ocp.3/helper.12# cat AIN4
          1460
          root@rbone:/sys/devices/ocp.3/helper.12# cat AIN4
          1798
          root@rbone:/sys/devices/ocp.3/helper.12# cat AIN4
          1798
          root@rbone:/sys/devices/ocp.3/helper.12# cat AIN4
          1460
          root@rbone:/sys/devices/ocp.3/helper.12# cat AIN4
          1460
          root@rbone:/sys/devices/ocp.3/helper.12# cat AIN4
          1460
          root@rbone:/sys/devices/ocp.3/helper.12# cat AIN4
          0



          And another example, showing relation to the number of
pins
in
          use.

          1.8v to AIN4
          root@rbone:/sys/devices/ocp.3/helper.12# cat AIN4
          1460
          root@rbone:/sys/devices/ocp.3/helper.12# grep . AIN[0-3]
          AIN0:1697
          AIN1:1298
          AIN2:1524
          AIN3:816
          root@rbone:/sys/devices/ocp.3/helper.12# cat AIN4
          1798

          0v to AIN4
          root@rbone:/sys/devices/ocp.3/helper.12# cat AIN4
          1798
          root@rbone:/sys/devices/ocp.3/helper.12# cat AIN4
          1460
          root@rbone:/sys/devices/ocp.3/helper.12# cat AIN4
          1460
          root@rbone:/sys/devices/ocp.3/helper.12# cat AIN4
          1460
          root@rbone:/sys/devices/ocp.3/helper.12# cat AIN4
          0

          1.8v to AIN4
          root@rbone:/sys/devices/ocp.3/helper.12# cat AIN4
          0
          root@rbone:/sys/devices/ocp.3/helper.12# cat AIN4
          0
          root@rbone:/sys/devices/ocp.3/helper.12# cat AIN4
          0
          root@rbone:/sys/devices/ocp.3/helper.12# cat AIN4
          0
          root@rbone:/sys/devices/ocp.3/helper.12# cat AIN4
          1798

          --         Rob Mosher
          Senior Network and Software Engineer
          Hurricane Electric / AS6939






--
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


--
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




[Index of Archives]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Input]     [Linux Kernel]     [Linux SCSI]     [X.org]

  Powered by Linux