Re: [PATCH v3 2/4] dt-bindings: can: fixed-transceiver: Add new CAN fixed transceiver bindings
From: Franklin S Cooper Jr
Date: Thu Aug 03 2017 - 12:39:11 EST
On 08/03/2017 07:22 AM, Sergei Shtylyov wrote:
> 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@xxxxxx>
>>>> ---
>>>> .../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...
Your right. I wasn't trying to imply that it does. What I meant was that
having a node named "can-transceiver" may be a bit confusing in the
future if can transceiver drivers are created. Prefix of "fixed" atleast
to me makes it clear that this is something unique or a generic
transceiver with limitations. Similar to "fixed-link" which is for MACs
not connected to MDIO managed phy. Calling this subnode
"can-transceiver" to me would be like renaming "fixed-link" to "phy".
>
>> So would "fixed-can-transceiver" be
>> ok or do you want to go with can-transceiver?
>
> I'm somewhat perplexed at this point...
If my reasoning still didn't change your views then I'll make the switch.
>
> MBR, Sergei