linux-kernel - Re: [PATCH v3 2/4] dt-bindings: can: fixed-transceiver: Add new CAN fixed transceiver bindings

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Message-ID: <86d78a36-04c2-7036-636c-7326a4c1c6b0@cogentembedded.com>
Date:   Thu, 3 Aug 2017 15:22:55 +0300
From:   Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:     Franklin S Cooper Jr <fcooper@...com>,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        netdev@...r.kernel.org, linux-can@...r.kernel.org,
        wg@...ndegger.com, mkl@...gutronix.de, robh+dt@...nel.org,
        quentin.schulz@...e-electrons.com, dev.kurt@...dijck-laurijssen.be,
        andrew@...n.ch, socketcan@...tkopp.net
Subject: Re: [PATCH v3 2/4] dt-bindings: can: fixed-transceiver: Add new CAN
 fixed transceiver bindings

On 08/03/2017 12:48 PM, Franklin S Cooper Jr wrote:

>>> Add documentation to describe usage of the new fixed transceiver binding.
>>> This new binding is applicable for any CAN device therefore it exists as
>>> its own document.
>>>
>>> Signed-off-by: Franklin S Cooper Jr <fcooper@...com>
>>> ---
>>>    .../bindings/net/can/fixed-transceiver.txt         | 24
>>> ++++++++++++++++++++++
>>>    1 file changed, 24 insertions(+)
>>>    create mode 100644
>>> Documentation/devicetree/bindings/net/can/fixed-transceiver.txt
>>>
>>> diff --git
>>> a/Documentation/devicetree/bindings/net/can/fixed-transceiver.txt
>>> b/Documentation/devicetree/bindings/net/can/fixed-transceiver.txt
>>> new file mode 100644
>>> index 0000000..2f58838b
>>> --- /dev/null
>>> +++ b/Documentation/devicetree/bindings/net/can/fixed-transceiver.txt
>>> @@ -0,0 +1,24 @@
>>> +Fixed transceiver Device Tree binding
>>> +------------------------------
>>> +
>>> +CAN transceiver typically limits the max speed in standard CAN and
>>> CAN FD
>>> +modes. Typically these limitations are static and the transceivers
>>> themselves
>>> +provide no way to detect this limitation at runtime. For this situation,
>>> +the "fixed-transceiver" node can be used.
>>> +
>>> +Required Properties:
>>> + max-bitrate:    a positive non 0 value that determines the max
>>> +        speed that CAN/CAN-FD can run. Any other value
>>> +        will be ignored.
>>> +
>>> +Examples:
>>> +
>>> +Based on Texas Instrument's TCAN1042HGV CAN Transceiver
>>> +
>>> +m_can0 {
>>> +    ....
>>> +    fixed-transceiver@0 {
>>
>>     The <unit-address> (after @) must only be specified if there's "reg"
> 
> Sorry. Fixed this in my v2 and some how it came back. Will fix.
> 
>> prop in the device node. Also, please name the node "can-transceiver@"
>> to be more in line with the DT spec. which requires generic node names.
> 
> Its possible for future can transceivers drivers to be created. So I

    So what? Ah, you are using the node name to match in the CAN drivers...

> thought including fixed was important to indicate that this is a "dumb"
> transceiver similar to "fixed-link".

    I'm not sure the "fixed-link" MAC subnode assumed any transceiver at all...

> So would "fixed-can-transceiver" be
> ok or do you want to go with can-transceiver?

    I'm somewhat perplexed at this point...

MBR, Sergei