From: "Ceclan, Dumitru" <mitrutzceclan@gmail.com>
To: David Lechner <dlechner@baylibre.com>
Cc: dumitru.ceclan@analog.com, Lars-Peter Clausen <lars@metafoo.de>,
Michael Hennerich <Michael.Hennerich@analog.com>,
Jonathan Cameron <jic23@kernel.org>,
Rob Herring <robh@kernel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
Conor Dooley <conor+dt@kernel.org>,
linux-iio@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/6] dt-bindings: adc: ad7173: add support for ad411x
Date: Thu, 4 Apr 2024 16:08:56 +0300 [thread overview]
Message-ID: <aa84a3c5-a3e6-4c76-9b67-624ed8d8c704@gmail.com> (raw)
In-Reply-To: <CAMknhBHhxi7mN88+peU7BGkzSP2vtipCuvM-XfQzgusqKvARsg@mail.gmail.com>
On 03/04/2024 18:22, David Lechner wrote:
> On Wed, Apr 3, 2024 at 2:50 AM Ceclan, Dumitru <mitrutzceclan@gmail.com> wrote:
>> On 02/04/2024 00:16, David Lechner wrote:
>>> On Mon, Apr 1, 2024 at 2:37 PM David Lechner <dlechner@baylibre.com> wrote:
>>>> On Mon, Apr 1, 2024 at 10:10 AM Dumitru Ceclan via B4 Relay
>>>> <devnull+dumitru.ceclan.analog.com@kernel.org> wrote:
>>>>> From: Dumitru Ceclan <dumitru.ceclan@analog.com>
>>>>>
>> ...
>>
>>>>> properties:
>>>>> reg:
>>>>> + description:
>>>>> + Reg values 16-19 are only permitted for ad4111/ad4112 current channels.
>>>>> minimum: 0
>>>>> - maximum: 15
>>>>> + maximum: 19
>>>> This looks wrong. Isn't reg describing the number of logical channels
>>>> (# of channel config registers)?
>>>>
>>>> After reviewing the driver, I see that > 16 is used as a way of
>>>> flagging current inputs, but still seems like the wrong way to do it.
>>>> See suggestion below.
>>>>
>>>>> diff-channels:
>>>>> + description:
>>>>> + For using current channels specify only the positive channel.
>>>>> + (IIN2+, IIN2−) -> diff-channels = <2 0>
>>>> I find this a bit confusing since 2 is already VIN2 and 0 is already
>>>> VIN0. I think it would make more sense to assign unique channel
>>>> numbers individually to the negative and positive current inputs.
>>>> Also, I think it makes sense to use the same numbers that the
>>>> registers in the datasheet use (8 - 11 for negative and 12 to 15 for
>>>> positive).
>>>>
>>>> So: (IIN2+, IIN2−) -> diff-channels = <13 10>
>>> Thinking about this a bit more...
>>>
>>> Since the current inputs have dedicated pins and aren't mix-and-match
>>> with multiple valid wiring configurations like the voltage inputs, do
>>> we even need to describe them in the devicetree?
>>>
>>> In the driver, the current channels would just be hard-coded like the
>>> temperature channel since there isn't any application-specific
>>> variation.
>> Sure, but we still need to offer the user a way to configure which
>> current inputs he wants and if they should use bipolar or unipolar coding.
> From the datasheet, it looks like only positive current input is
> allowed so I'm not sure bipolar applies here. But, yes, if there is
> some other variation in wiring or electrical signal that needs to be
> describe here, then it makes sense to allow a channel configuration
> node for it.
AD4111 datasheet pg.29:
When the ADC is configured for bipolar operation, the output
code is offset binary with a negative full-scale voltage resulting
in a code of 000 … 000, a zero differential input voltage resulting in
a code of 100 … 000, and a positive full-scale input voltage
resulting in a code of 111 … 111. The output code for any
analog input voltage can be represented as
Code = 2^(N – 1) × ((V_IN × 0.1/V REF) + 1)
The output code for any input current is represented as
Code = 2^(N − 1) × ((I_IN × 50 Ω/V REF) + 1)
I would say bipolar applies here, not a great idea because of the limitation on
the negative side (Input Current Range min:−0.5 max:+24 mA) so still, the option
is available.
next prev parent reply other threads:[~2024-04-04 13:09 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-01 15:32 [PATCH 0/6] Add support for AD411x Dumitru Ceclan via B4 Relay
2024-04-01 15:32 ` [PATCH 1/6] dt-bindings: adc: ad7173: add support for ad411x Dumitru Ceclan via B4 Relay
2024-04-01 19:37 ` David Lechner
2024-04-01 20:22 ` David Lechner
2024-04-03 7:45 ` Ceclan, Dumitru
2024-04-03 10:08 ` Ceclan, Dumitru
2024-04-03 15:14 ` David Lechner
2024-04-01 21:16 ` David Lechner
2024-04-03 7:50 ` Ceclan, Dumitru
2024-04-03 15:22 ` David Lechner
2024-04-04 13:08 ` Ceclan, Dumitru [this message]
2024-04-06 14:26 ` Jonathan Cameron
2024-04-09 8:10 ` Ceclan, Dumitru
2024-04-03 7:43 ` Ceclan, Dumitru
2024-04-03 15:40 ` David Lechner
2024-04-06 14:53 ` Jonathan Cameron
2024-04-09 8:08 ` Ceclan, Dumitru
2024-04-13 10:49 ` Jonathan Cameron
2024-04-15 18:42 ` Ceclan, Dumitru
2024-04-20 14:33 ` Jonathan Cameron
2024-04-23 8:18 ` Ceclan, Dumitru
2024-04-28 17:13 ` Jonathan Cameron
2024-05-09 13:48 ` Ceclan, Dumitru
2024-05-15 21:42 ` David Lechner
2024-05-16 8:18 ` Ceclan, Dumitru
2024-04-01 15:32 ` [PATCH 2/6] iio: adc: ad7173: fix buffers enablement for ad7176-2 Dumitru Ceclan via B4 Relay
2024-04-01 19:38 ` David Lechner
2024-04-06 14:56 ` Jonathan Cameron
2024-04-08 16:40 ` Ceclan, Dumitru
2024-04-13 10:50 ` Jonathan Cameron
2024-04-01 15:32 ` [PATCH 3/6] iio: adc: ad7173: refactor channel configuration parsing Dumitru Ceclan via B4 Relay
2024-04-01 19:39 ` David Lechner
2024-04-03 10:01 ` Ceclan, Dumitru
2024-04-03 15:55 ` David Lechner
2024-04-01 15:32 ` [PATCH 4/6] iio: adc: ad7173: refactor ain and vref selection Dumitru Ceclan via B4 Relay
2024-04-01 19:40 ` David Lechner
2024-04-03 10:03 ` Ceclan, Dumitru
2024-04-03 16:02 ` David Lechner
2024-04-06 15:03 ` Jonathan Cameron
2024-04-01 15:32 ` [PATCH 5/6] iio: adc: ad7173: Remove index from temp channel Dumitru Ceclan via B4 Relay
2024-04-01 19:40 ` David Lechner
2024-04-01 15:32 ` [PATCH 6/6] iio: adc: ad7173: Add support for AD411x devices Dumitru Ceclan via B4 Relay
2024-04-01 19:45 ` David Lechner
2024-04-02 14:00 ` David Lechner
2024-04-03 9:55 ` Ceclan, Dumitru
2024-04-03 9:53 ` Ceclan, Dumitru
2024-04-03 16:37 ` David Lechner
2024-04-06 15:10 ` Jonathan Cameron
2024-05-14 7:28 ` Ceclan, Dumitru
2024-04-01 21:53 ` David Lechner
2024-04-03 8:15 ` Ceclan, Dumitru
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