On 5/7/2012 4:17 PM, Michael Hennerich wrote:
On 05/07/2012 05:00 PM, Michael Hennerich wrote:
On 03/22/2012 10:10 AM, Jonathan Cameron wrote:
On 3/22/2012 8:52 AM, Michael Hennerich wrote:
On 03/21/2012 08:34 PM, Jonathan Cameron wrote:
On 02/22/2012 12:36 PM, michael.hennerich@xxxxxxxxxx wrote:
From: Michael Hennerich<michael.hennerich@xxxxxxxxxx>
Sorry for the slow response on this one. Been off sick...
Anyhow, I'm still not sure what the right interface for this type
of device is.
The obvious options are:
1) Make gain an IIO type (doesn't make much sense as gain is only
going
to be of one particular existing type).
2) Have it as an IIO_ALTVOLTAGE channel as you have here and use
extend
name. Any real reason for picking altvoltage rather than voltage?
I'm open for advice. Since I made the amplifier being an OUT type
device
I chose IIO_ALTVOLTAGE analogous to our DDS/PLL drivers.
Some VGAs/PGAs work from DC, but typically VGAs are HF devices.
Hmm.. Don't suppose it really matters but we ought to aim for
consistency
(by review) at least. This particular part is DC through to 600MHz.
Clearly gain has the same meaning in either case (assuming it's
linear).
3) Make a change to core to allow a channel to have elements in
info_mask but not actually to have a raw access. Not entirely sure
how we will do that cleanly. Also it's not clear whether the gain
would be an IN or an OUT channel type!
Well - having the ability for channels without raw access element
would be of interest.
True enough. Cleanest way to do this that I can think of is to make
a tree
wide change to add the raw element to the info_mask. We could allow
for
a zero info_mask value actually being the equivalent of having only
a raw
channel. It's invasive but if we agreee it should be done now is
probably the
best time to do it (just post merge window etc).
Hi Jonathan,
Thanks for getting this in place.
Whilst here, we clearly need way of destinguishing values in DB from
linear
gains. Could add a new return type for read_raw callbacks?
Does something like this work for you?
Also wondering if we should introduce IIO_CHAN_INFO_GAIN
for amplifier type devices?
Thinking about it a bit more - why not have iio_chan_type:IIO_GAIN?
Lack of consistency with other devices. If we have a pga on the front
of an adc then the type is voltage and control is done via relevant info
element.
How is this any different?
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