Hi Vignesh,
would it be possible to add some more channel-specific settings ?
It would be nice to have allmost full control to the STEPCONFIGx register.
At least we need to write the bits
SEL_RFM_SWC_1_0
SEL_INM_SWC_3_0
SEL_RFP_SWC_2_0
In the current mainline version only (SEL_INP_SWC_3_0) is written.
So for the other bits "0" is value is used, for my point of view this is
not correct.
For example if we want to read a value from AIN5 the negative pin from adc
is muxed allways to AIN0.
In fact i can readout heavy jitter even if AIN5 is connected to ground -
after setting up negative adc pin within code (to use REFN) the readout
value is 0 as expected without nameable jitter.
If i short AIN0 also to ground, jitter is also eliminated.
Maybe this is also some fault of TI SoC ... in normal case somebody could
expect, that negative adc pin is equal even the Diff_CNTRL bit isn't set -
but in practice it isn't.
Also actually it isn't possible to make some accurate measurement due to
the fact that allways VDDA_ADC is used as positive reference.
So it would be nice to have control around this bits.
Whats your opinion around that?
best regards,
Hannes
----- Forwarded by Hannes Petermaier/Eggelsberg/AT/B&R on 07.04.2015 14:17
-----
From: Johannes Pointner <johannes.pointner@xxxxxxxxx>
To: hannes.petermaier@xxxxxxxxxxxxxxxxx
Date: 07.04.2015 13:58
Subject: Fwd: [PATCH 0/2] iio: ti_am335x_adc: Add optional DT
properties for tscadc
---------- Forwarded message ----------
From: Vignesh R <vigneshr@xxxxxx>
Date: 2015-03-31 13:12 GMT+02:00
Subject: [PATCH 0/2] iio: ti_am335x_adc: Add optional DT properties for
tscadc
To: Rob Herring <robh+dt@xxxxxxxxxx>, Pawel Moll <pawel.moll@xxxxxxx>,
Mark Rutland <mark.rutland@xxxxxxx>, Ian Campbell
<ijc+devicetree@xxxxxxxxxxxxxx>, Kumar Gala <galak@xxxxxxxxxxxxxx>,
Jonathan Cameron <jic23@xxxxxxxxxx>
Cc: Hartmut Knaack <knaack.h@xxxxxx>, Lars-Peter Clausen
<lars@xxxxxxxxxx>, Peter Meerwald <pmeerw@xxxxxxxxxx>, Dmitry Torokhov
<dmitry.torokhov@xxxxxxxxx>, Karol Wrona <k.wrona@xxxxxxxxxxx>, Jan
Kardell <jan.kardell@xxxxxxxxxx>, devicetree@xxxxxxxxxxxxxxx,
linux-kernel@xxxxxxxxxxxxxxx, linux-iio@xxxxxxxxxxxxxxx,
fcooper@xxxxxx, Vignesh R <vigneshr@xxxxxx>
Hi,
This patch adds optional DT properties for tscadc to set open delay,
sample delay and number of averages per sample for each adc channel.
Open delay, sample delay and averaging are some of the parameters that
affect the sampling rate and accuracy of the tscadc. Decreasing delays
and averaging helps to achieve higher sampling rates, while increasing
this parameters provides greater accuracy. Hence, this patch provides DT
properties to set the initial values for delays and number of averages
per sample. User space control via sysfs can be added later.
Vignesh R (2):
iio: adc: ti_am335x_adc: refactor DT parsing into a function
iio: adc: ti_am335x_adc: make sample delay, open delay, averaging DT
parameters
.../bindings/input/touchscreen/ti-tsc-adc.txt | 24 +++++++
drivers/iio/adc/ti_am335x_adc.c | 83
+++++++++++++++++-----
2 files changed, 91 insertions(+), 16 deletions(-)
--
1.9.1
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