Hi,

On 08/19, Krzysztof Kozlowski wrote:

On 18/08/2025 23:04, Jonathan Santos wrote:

quoted

On 08/16, Jonathan Cameron wrote:

quoted

On Thu, 14 Aug 2025 08:03:23 +0200
Krzysztof Kozlowski [off-list ref] wrote:

quoted

On 14/08/2025 00:39, Jonathan Santos wrote:

quoted

quoted

quoted

 
+  adi,aaf-gain:
+    description: |
+      Specifies the gain of the Analog Anti-Aliasing Filter (AAF) applied to the
+      ADC input, measured in milli-units. The AAF provides additional signal  

What is milli unit? Isn't gain in dB, so maybe you want mB? Quite
unpopular to see mB, but we cannot use 1/100 of dB, so I could
understand it.
 

Actually, the gain is expressed in V/V, not in dB. I may have phrased it poorly, but since
there are fractional values like 0.364 and 0.143, I chose to represent it
in milli-units.  

Why your reply to is corrupted:
"c3cf9b97-3883-4ebb-a2ed-0033adebda87@kernel.org"?


What sort of unit is milli-unit? Isn't this 1/1000 of some BASE unit,
but you do not have here a base?

I think you want just basis point if this is V/V (already in common
property suffixes)

Nice. I didn't know about -bp.   That does sound like a good choice for ratio
stuff and here would be 100x larger actual values which is fine.

Yes, it would be, but the here it is 1000x larger than the
actual value (1/1000 V/V). I don't see another unit in

Huh? How? 1000x larger would be = 1... This makes no sense...

quoted

property-units.yaml for this specifc case. Maybe using -milli suffix
like in 'adi,ad4000.yaml' and 'adi,ad7380.yaml'?

After having a look at the data sheets for these parts (AD7768-1, ADAQ7767-1,
ADAQ7768-1, ADAQ7769-1), I think this indeed has similar semantics to
adi,gain-milli. The data sheet says the AAF selection has an impact on the -3dB
cutoff frequency but, for a given ODR, there is no difference between the
reported −3 dB Bandwidth (kHz) in Table 12, Table 32, and Table 35 from
AD7768-1, ADAQ7767-1, and ADAQ7769-1, respectively. So, looks like this is just 
about signal amplification/attenuation and so the use of adi,gain-milli sounds
appropriate to me.

Considering the AAF doesn't really impact the -3dB cutoff frequency, maybe the
property could be documented like:

  adi,gain-milli:
    description: |
	  Specifies the gain applied by the Analog Anti-Aliasing Filter (AAF) to the
	  ADC input (in milli units). The hardware gain is determined by which input
      pin(s) the signal goes through into the AAF. The possible connections are:
      * For the ADAQ7767-1: input signal connected to IN1±, IN2± or IN3±.
      * For the ADAQ7769-1: OUT_PGA pin connected to IN1_AAF+, IN2_AAF+, or
        IN3_AAF+.
      If not present, default to 1000 (no actual gain applied).
    $ref: /schemas/types.yaml#/definitions/uint16
    enum: [143, 364, 1000]
    default: 1000

Would something along those lines make sense for these devices?

Best regards,
Marcelo