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
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