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    SubjectRe: [PATCH 1/3] IIO: Direct digital synthesis abi documentation
    On 12/14/10 09:49, Hennerich, Michael wrote:
    >> Jonathan Cameron wrote on 2010-12-13:
    >> On 12/13/10 16:27, michael.hennerich@analog.com wrote:
    >>> From: Michael Hennerich <michael.hennerich@analog.com>
    >>>
    >>> Changes since RFC/v1:
    >>> IIO: Apply list review feedback:
    >>>
    >>> Apply list review feedback:
    >>> Restructure documentation according to list feedback.
    >>> Rename attributes to fit IIO convention used in other drivers.
    >>> Fix typos.
    >>> Provide ddsX_out_enable as opposed to ddsX_out_disable
    >> Hi Michael,
    >>
    >> This is more or less there. A few minor queries / suggestions
    >> inline. The only major one is the mixture of X and [n] notation
    >> for the various indicies. I 'think' all our docs have now moved
    >> to the X notation. (if not then I have messed up!)
    >>
    >> I am happy with all the actual attributes. All remaining issues
    >> are to do with the descriptions of what they do!
    >>
    >> Thanks,
    >>
    >> Jonathan
    >>>
    >>> Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
    >>> Reviewed-by: Jonathan Cameron <jic23@cam.ac.uk>
    >>> ---
    >>> .../staging/iio/Documentation/sysfs-bus-iio-dds | 94
    >> ++++++++++++++++++++
    >>> 1 files changed, 94 insertions(+), 0 deletions(-)
    >>> create mode 100644 drivers/staging/iio/Documentation/sysfs-bus-iio-
    >> dds
    >>>
    >>> diff --git a/drivers/staging/iio/Documentation/sysfs-bus-iio-dds
    >> b/drivers/staging/iio/Documentation/sysfs-bus-iio-dds
    >>> new file mode 100644
    >>> index 0000000..6791174
    >>> --- /dev/null
    >>> +++ b/drivers/staging/iio/Documentation/sysfs-bus-iio-dds
    >>> @@ -0,0 +1,94 @@
    >>> +
    >>> +What: /sys/bus/iio/devices/device[n]/ddsX_freqY
    >> We have a hybrid here of the old indexing schemed (device[n]) and the
    >> new. Either just shorten then form to
    >> /sys/bus/iio/.../ddsX_freqY or use
    >> /sys/bus/iio/devices/deviceX/ddsY_freqZ and update below appropriately.
    >>> +KernelVersion: 2.6.37
    >>> +Contact: linux-iio@vger.kernel.org
    >>> +Description:
    >>> + Stores frequency into tuning word register Y.
    >> Technically it might not be a register? Dropping 'register' doesn't
    >> to my mind change the meaning but makes it marginally more general.
    >
    > ok
    >
    >>> + There can be more than one ddsX_freqY file, which allows
    >> for
    >> If there is only one wouldn't it be ddsX_freq and correspond to direct
    >> control rather than dependant on the tunning word?
    >
    > I don't understand. In case there is only one ddsX_freqY file.
    > Then there is certainly no ddsX_freqsymbol or ddsX_pincontrol_freq_en file.
    Then what is the Y index for? It's always 0 so why not suppress it and
    just have ddsX_freq? Thus if there is a Y index there has to be more than 1.
    >
    >> The upshot of this
    >> is that there are always 0 or more than 1 ddsX_freqY file.
    >> Given we don't have any direct control cases yet that can be documented
    >> when/if the turn up. Hence change line above to..
    >> "There will be more than one ddsX_freqY file, which allows for"
    >
    > We can document the missing cases once we add parts that requires them.
    >
    >>> + pin controlled FSK Frequency Shift Keying
    >>> + (ddsX_pincontrol_freq_en is active) or the user can control
    >>> + the desired active tuning word by writing Y to the
    >>> + ddsX_freqsymbol file.
    >>> +
    >>> +What: /sys/bus/iio/devices/device[n]/ddsX_freqY_scale
    >>> +KernelVersion: 2.6.37
    >>> +Contact: linux-iio@vger.kernel.org
    >>> +Description:
    >>> + Scale to be applied to ddsX_freqY in order to obtain the
    >>> + desired value in Hz. If shared across all frequency
    >> registers
    >>> + Y is not present. It is also possible X is not present if
    >>> + shared across all channels.
    >>> +
    >>> +What: /sys/bus/iio/devices/device[n]/ddsX_freqsymbol
    >>> +KernelVersion: 2.6.37
    >>> +Contact: linux-iio@vger.kernel.org
    >>> +Description:
    >>> + Specifies the active output frequency tuning word. The
    >> value
    >>> + corresponds to the Y in ddsX_freqY. To exit this mode the
    >> user
    >>> + can write ddsX_pincontrol_freq_en or ddsX_out_disable file.
    >> Is it theoretically possible to read this value when pin control is on?
    >
    > Not with the AD9832/35 AD9833/34, some other DDS parts allow register readouts.
    > Depending on the implementation of the device in question. It might be possible
    > To read back the current hardware state.
    >
    > I'll add the read method.
    >
    >>> +
    >>> +What: /sys/bus/iio/devices/device[n]/ddsX_phaseY
    >>> +KernelVersion: 2.6.37
    >>> +Contact: linux-iio@vger.kernel.org
    >>> +Description:
    >>> + Stores phase into phase register Y.
    >> Again, the mention of 'register' is a bit leading. It's always a
    >> register
    >> so far but at least in theory it could be say several registers...
    >
    > I'll change.
    >
    >>> + There can be more than one ddsX_phaseY file, which allows
    >> for
    >> Again, 'There will be'
    >
    > ok
    >
    >>> + pin controlled PSK Phase Shift Keying
    >>> + (ddsX_pincontrol_phase_en is active) or the user can
    >>> + control the desired phase Y which is added to the phase
    >>> + accumulator output by writing Y to the en_phase file.
    >>> +
    >>> +What: /sys/bus/iio/devices/device[n]/ddsX_phaseY_scale
    >>> +KernelVersion: 2.6.37
    >>> +Contact: linux-iio@vger.kernel.org
    >>> +Description:
    >>> + Scale to be applied to ddsX_phaseY in order to obtain the
    >>> + desired value in rad. If shared across all phase registers
    >>> + Y is not present. It is also possible X is not present if
    >>> + shared across all channels.
    >>> +
    >>> +What: /sys/bus/iio/devices/device[n]/ddsX_phasesymbol
    >>> +KernelVersion: 2.6.37
    >>> +Contact: linux-iio@vger.kernel.org
    >>> +Description:
    >>> + Specifies the active phase Y which is added to the phase
    >>> + accumulator output. The value corresponds to the Y in
    >>> + ddsX_phaseY. To exit this mode the user can write
    >>> + ddsX_pincontrol_phase_en or disable file.
    >>> +
    >>> +What: /sys/bus/iio/devices/device[n]/ddsX_pincontrol_en
    >>> +What:
    >> /sys/bus/iio/devices/device[n]/ddsX_pincontrol_freq_en
    >>> +What:
    >> /sys/bus/iio/devices/device[n]/ddsX_pincontrol_phase_en
    >>> +KernelVersion: 2.6.37
    >>> +Contact: linux-iio@vger.kernel.org
    >>> +Description:
    >>> + ddsX_pincontrol_en: Both, the active frequency and phase is
    >>> + controlled by the respective phase and frequency control
    >> inputs.
    >>> + In case the device in question allows to independent
    >> controls,
    >>> + then there are dedicated files (ddsX_pincontrol_freq_en,
    >>> + ddsX_pincontrol_phase_en).
    >>> +
    >>> +What: /sys/bus/iio/devices/device[n]/ddsX_out_enable
    >>> +What: /sys/bus/iio/devices/device[n]/ddsX_outY_enable
    >>> +KernelVersion: 2.6.37
    >>> +Contact: linux-iio@vger.kernel.org
    >>> +Description:
    >>> + ddsX_out_enable: Enables signal generation on all outputs
    >>> + of channel X.
    >>> + ddsX_outY_enable: Enables signal generation on output Y,
    >>> + of channel X.
    >> This description takes a rather different form from similar ones above.
    >> Perhaps it should read...
    >>
    >> ddsX_outY_enable controls signal generation on output Y of channel X. Y
    >> may
    >> be suppressed if all channels are controlled together.
    >>
    >> (we can add supression of X to the description if it ever occurs!)
    >
    > ok
    >
    >>> +
    >>> +What: /sys/bus/iio/devices/device[n]/ddsX_outY_wavetype
    >>> +KernelVersion: 2.6.37
    >>> +Contact: linux-iio@vger.kernel.org
    >>> +Description:
    >>> + Specifies the output waveform.
    >>> + (sine, triangle, ramp, square, ...)
    >>> + For a list of available output waveform options read
    >>> + available_output_modes.
    >>> +
    >>> +What:
    >> /sys/bus/iio/devices/device[n]/ddsX_outY_wavetype_available
    >>> +KernelVersion: 2.6.37
    >>> +Contact: linux-iio@vger.kernel.org
    >>> +Description:
    >>> + Lists all available output waveform options.
    >>> --
    >>> 1.6.0.2
    >>>
    >>>
    >
    >



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