How to get device supported ctrl modes from userspace

How to get device supported ctrl modes from userspace

[Lars Susaas]

Hi,

I would like find out how to get information about which control modes
the device supports from userspace.
Ctrlmode as in CAN_CTRLMODE_LISTENONLY

In the driver code is looks like it is found in
priv->can.ctrlmode_supported, but how do i get it from userspace?

I am unable to find any information about this.

Lars

Re: How to get device supported ctrl modes from userspace

[Wolfgang Grandegger]

Hello Lars,

Am 09.03.2017 um 21:38 schrieb Lars Susaas:
> Hi,
>
> I would like find out how to get information about which control modes
> the device supports from userspace.
> Ctrlmode as in CAN_CTRLMODE_LISTENONLY
>
> In the driver code is looks like it is found in
> priv->can.ctrlmode_supported, but how do i get it from userspace?
>
> I am unable to find any information about this.

You could probe the mode. If it's not supported, EOPNOTSUP will be returned:

   # ip -d -s link set can0 type can one-shot on
   RTNETLINK answers: Operation not supported

Thinking about it... It would be nice to list the supported modes with:

   # ip -d link show can0

Wolfgang.

Re: How to get device supported ctrl modes from userspace

[Lars Susaas]

>> I would like find out how to get information about which control modes
>> the device supports from userspace.
>> Ctrlmode as in CAN_CTRLMODE_LISTENONLY
>>
>> In the driver code is looks like it is found in
>> priv->can.ctrlmode_supported, but how do i get it from userspace?
>>
>> I am unable to find any information about this.
>
> You could probe the mode. If it's not supported, EOPNOTSUP will be returned:
>
>   # ip -d -s link set can0 type can one-shot on
>   RTNETLINK answers: Operation not supported

Thanks for the tip, it works!
For the record, trying to turn the modes off instead of on have the
same results and work with can-fd out of the box.

> Thinking about it... It would be nice to list the supported modes with:
>
>   # ip -d link show can0

Yes, that is what i was dreaming/looking for :)

Re: How to get device supported ctrl modes from userspace

[Wolfgang Grandegger]

Am 13.03.2017 um 22:26 schrieb Lars Susaas:
>>> I would like find out how to get information about which control modes
>>> the device supports from userspace.
>>> Ctrlmode as in CAN_CTRLMODE_LISTENONLY
>>>
>>> In the driver code is looks like it is found in
>>> priv->can.ctrlmode_supported, but how do i get it from userspace?
>>>
>>> I am unable to find any information about this.
>>
>> You could probe the mode. If it's not supported, EOPNOTSUP will be returned:
>>
>>   # ip -d -s link set can0 type can one-shot on
>>   RTNETLINK answers: Operation not supported
>
> Thanks for the tip, it works!
> For the record, trying to turn the modes off instead of on have the
> same results and work with can-fd out of the box.

Sounds like a bug. Could be a bit more verbose? What does not work?

>
>> Thinking about it... It would be nice to list the supported modes with:
>>
>>   # ip -d link show can0
>
> Yes, that is what i was dreaming/looking for :)

The supported feature flag is not yet available trough via netlink 
interface.

Wolfgang.

Re: How to get device supported ctrl modes from userspace

[Lars Susaas]

On Tue, Mar 14, 2017 at 8:27 AM, Wolfgang Grandegger <wg@grandegger.com> wrote:
> Am 13.03.2017 um 22:26 schrieb Lars Susaas:
>>>>
>>>> I would like find out how to get information about which control modes
>>>> the device supports from userspace.
>>>> Ctrlmode as in CAN_CTRLMODE_LISTENONLY
>>>>
>>>> In the driver code is looks like it is found in
>>>> priv->can.ctrlmode_supported, but how do i get it from userspace?
>>>>
>>>> I am unable to find any information about this.
>>>
>>>
>>> You could probe the mode. If it's not supported, EOPNOTSUP will be
>>> returned:
>>>
>>>   # ip -d -s link set can0 type can one-shot on
>>>   RTNETLINK answers: Operation not supported
>>
>>
>> Thanks for the tip, it works!
>> For the record, trying to turn the modes off instead of on have the
>> same results and work with can-fd out of the box.
>
>
> Sounds like a bug. Could be a bit more verbose? What does not work?

Using ubuntu 16.10 (Linux 4.8.0-41-generic) and testing with  a
'pcan-usb pro fd'
As far as i can see in the sourcecode it supports triple-sampling,
listen-only and fd

Just startet the computer and connected the can device

#ip -d -s link set can0 type can fd on
RTNETLINK answers: Operation not supported
#ip -d -s link set can0 type can fd off
(no error)

If I try to turn modes on to test support for fd support i would fail.
But it looks like i can detect support for fd by trying to turn it off.

I would need the change mtu to be able to turn on fd.
As i just want to find out if a feature is supported, trying to turn
it off looks like more universal way of testing

Testing some more to check that it works on other modes to.
#ip -d -s link set can0 type can loopback on
RTNETLINK answers: Operation not supported
#ip -d -s link set can0 type can loopback off
RTNETLINK answers: Operation not supported
#ip -d -s link set can0 type can listen-only on
#ip -d -s link set can0 type can listen-only off
(no error)

Testing the rest of the modes gives the same result when i try to turn
it on and off, but fd mode differs.

>>> Thinking about it... It would be nice to list the supported modes with:
>>>
>>>   # ip -d link show can0
>>
>>
>> Yes, that is what i was dreaming/looking for :)
>
>
> The supported feature flag is not yet available trough via netlink
> interface.
I understand and thanks for taking the time to help me out

Re: How to get device supported ctrl modes from userspace

[Wolfgang Grandegger]

Am 14.03.2017 um 17:50 schrieb Lars Susaas:
> On Tue, Mar 14, 2017 at 8:27 AM, Wolfgang Grandegger <wg@grandegger.com> wrote:
>> Am 13.03.2017 um 22:26 schrieb Lars Susaas:
>>>>>
>>>>> I would like find out how to get information about which control modes
>>>>> the device supports from userspace.
>>>>> Ctrlmode as in CAN_CTRLMODE_LISTENONLY
>>>>>
>>>>> In the driver code is looks like it is found in
>>>>> priv->can.ctrlmode_supported, but how do i get it from userspace?
>>>>>
>>>>> I am unable to find any information about this.
>>>>
>>>>
>>>> You could probe the mode. If it's not supported, EOPNOTSUP will be
>>>> returned:
>>>>
>>>>   # ip -d -s link set can0 type can one-shot on
>>>>   RTNETLINK answers: Operation not supported
>>>
>>>
>>> Thanks for the tip, it works!
>>> For the record, trying to turn the modes off instead of on have the
>>> same results and work with can-fd out of the box.
>>
>>
>> Sounds like a bug. Could be a bit more verbose? What does not work?
>
> Using ubuntu 16.10 (Linux 4.8.0-41-generic) and testing with  a
> 'pcan-usb pro fd'
> As far as i can see in the sourcecode it supports triple-sampling,
> listen-only and fd
>
> Just startet the computer and connected the can device
>
> #ip -d -s link set can0 type can fd on
> RTNETLINK answers: Operation not supported
> #ip -d -s link set can0 type can fd off
> (no error)
>
> If I try to turn modes on to test support for fd support i would fail.
> But it looks like i can detect support for fd by trying to turn it off.
>
> I would need the change mtu to be able to turn on fd.
> As i just want to find out if a feature is supported, trying to turn
> it off looks like more universal way of testing
>
> Testing some more to check that it works on other modes to.
> #ip -d -s link set can0 type can loopback on
> RTNETLINK answers: Operation not supported
> #ip -d -s link set can0 type can loopback off
> RTNETLINK answers: Operation not supported
> #ip -d -s link set can0 type can listen-only on
> #ip -d -s link set can0 type can listen-only off
> (no error)
>
> Testing the rest of the modes gives the same result when i try to turn
> it on and off, but fd mode differs.

See:

   http://lxr.free-electrons.com/source/drivers/net/can/dev.c#L847

You need to provide proper bittiming parameters as well. Turning the 
ctrlmode off does nothing if it's not already on.

Wolfgang.

Re: How to get device supported ctrl modes from userspace

[Lars Susaas]

On Tue, Mar 14, 2017 at 8:12 PM, Wolfgang Grandegger <wg@grandegger.com> wrote:
> Am 14.03.2017 um 17:50 schrieb Lars Susaas:
>>
>> On Tue, Mar 14, 2017 at 8:27 AM, Wolfgang Grandegger <wg@grandegger.com>
>> wrote:
>>>
>>> Am 13.03.2017 um 22:26 schrieb Lars Susaas:
>>>>>>
>>>>>>
>>>>>> I would like find out how to get information about which control modes
>>>>>> the device supports from userspace.
>>>>>> Ctrlmode as in CAN_CTRLMODE_LISTENONLY
>>>>>>
>>>>>> In the driver code is looks like it is found in
>>>>>> priv->can.ctrlmode_supported, but how do i get it from userspace?
>>>>>>
>>>>>> I am unable to find any information about this.
>>>>>
>>>>>
>>>>>
>>>>> You could probe the mode. If it's not supported, EOPNOTSUP will be
>>>>> returned:
>>>>>
>>>>>   # ip -d -s link set can0 type can one-shot on
>>>>>   RTNETLINK answers: Operation not supported
>>>>
>>>>
>>>>
>>>> Thanks for the tip, it works!
>>>> For the record, trying to turn the modes off instead of on have the
>>>> same results and work with can-fd out of the box.
>>>
>>>
>>>
>>> Sounds like a bug. Could be a bit more verbose? What does not work?
>>
>>
>> Using ubuntu 16.10 (Linux 4.8.0-41-generic) and testing with  a
>> 'pcan-usb pro fd'
>> As far as i can see in the sourcecode it supports triple-sampling,
>> listen-only and fd
>>
>> Just startet the computer and connected the can device
>>
>> #ip -d -s link set can0 type can fd on
>> RTNETLINK answers: Operation not supported
>> #ip -d -s link set can0 type can fd off
>> (no error)
>>
>> If I try to turn modes on to test support for fd support i would fail.
>> But it looks like i can detect support for fd by trying to turn it off.
>>
>> I would need the change mtu to be able to turn on fd.
>> As i just want to find out if a feature is supported, trying to turn
>> it off looks like more universal way of testing
>>
>> Testing some more to check that it works on other modes to.
>> #ip -d -s link set can0 type can loopback on
>> RTNETLINK answers: Operation not supported
>> #ip -d -s link set can0 type can loopback off
>> RTNETLINK answers: Operation not supported
>> #ip -d -s link set can0 type can listen-only on
>> #ip -d -s link set can0 type can listen-only off
>> (no error)
>>
>> Testing the rest of the modes gives the same result when i try to turn
>> it on and off, but fd mode differs.
>
>
> See:
>
>   http://lxr.free-electrons.com/source/drivers/net/can/dev.c#L847
>
> You need to provide proper bittiming parameters as well. Turning the
> ctrlmode off does nothing if it's not already on.
>
Oh, I see.
Will check by turning feature on then, and make sure bittiming is set
before testing for fd