Bit rate configuration of PEAK USB devices

Bit rate configuration of PEAK USB devices

[Heinz-Jürgen Oertel]

Hello,

I tried
 ip link set can0 type can bitrate 125000
and I tried socketcanlib
can_set_bitrate("can0", 125000);
but everytime got the error 
RTNETLINK answers: Operation not permitted.
Reading the "PCAN driver for Linux - User Manual" v7.1
I could not find instructions to set the bit rate for netdev.
 
Who knows the best and/or correct way?

 Regards
   Heinz

Re: [Socketcan-users] Bit rate configuration of PEAK USB devices

[Oliver Hartkopp]

Hello Heinz,

On 15.11.2011 15:13, Heinz-Jürgen Oertel wrote:

> I tried
>  ip link set can0 type can bitrate 125000
> and I tried socketcanlib
> can_set_bitrate("can0", 125000);
> but everytime got the error 
> RTNETLINK answers: Operation not permitted.
> Reading the "PCAN driver for Linux - User Manual" v7.1
> I could not find instructions to set the bit rate for netdev.

>

> Who knows the best and/or correct way?


Me :-)

The netdev support inside the PEAK driver is a bit like an add-on to the
original character device driver.

Since PCAN Linux driver 6.0 you can compile the PEAK driver with netdev
support which means that for each detected CAN device an 'additional'
netdevice is being created.

Unfortunately these netdevices only support the sending and receiving of CAN
frames BUT no configuration of the CAN devices. This is still to be done via
the chardev inodes in /dev/pcanXX ..

See "PCAN driver for Linux - User Manual" v7.1, page 22

---

The 'ndev' column shows the network device assignment. For
assignment of bitrates to network devices you can either set the
desired bit rate as module load parameter or you can assign the bit
rate after loading the driver with a simple command line invocation
like:

    echo "i 0x4914 e" > /dev/pcan0

For this reason it is important to create the chardev-device-entries,
too. If your target does no create the device files automatically with
UDEV you have to run with the script

    ./pcan_make_devices 2

even if only the netdev driver is used.

---

Indeed i was already thinking about the integration of the netlink-based
configuration interface (of the mainline kernel) into the PCAN driver.

But finally this would be another add-on ... IMHO the better approach would be
to support the PEAK hardware in the form of mainline drivers, like we already
have for the PCAN PCI and PCAN ISA hardware. A future PCAN USB driver could be
created on the basis of the existing USB CAN adapter from ESD and EMS.

Best regards,
Oliver

Re: [Socketcan-users] Bit rate configuration of PEAK USB devices

[Oliver Hartkopp]

I forgot to mention that you can also use the PCAN ioctl() interface on the
PEAK chardevices or their pcanlib ...


On 15.11.2011 19:09, Oliver Hartkopp wrote:

> Hello Heinz,
> 
> On 15.11.2011 15:13, Heinz-Jürgen Oertel wrote:
> 
>> I tried
>>  ip link set can0 type can bitrate 125000
>> and I tried socketcanlib
>> can_set_bitrate("can0", 125000);
>> but everytime got the error 
>> RTNETLINK answers: Operation not permitted.
>> Reading the "PCAN driver for Linux - User Manual" v7.1
>> I could not find instructions to set the bit rate for netdev.
> 
>>
> 
>> Who knows the best and/or correct way?
> 
> 
> Me :-)
> 
> The netdev support inside the PEAK driver is a bit like an add-on to the
> original character device driver.
> 
> Since PCAN Linux driver 6.0 you can compile the PEAK driver with netdev
> support which means that for each detected CAN device an 'additional'
> netdevice is being created.
> 
> Unfortunately these netdevices only support the sending and receiving of CAN
> frames BUT no configuration of the CAN devices. This is still to be done via
> the chardev inodes in /dev/pcanXX ..
> 
> See "PCAN driver for Linux - User Manual" v7.1, page 22
> 
> ---
> 
> The 'ndev' column shows the network device assignment. For
> assignment of bitrates to network devices you can either set the
> desired bit rate as module load parameter or you can assign the bit
> rate after loading the driver with a simple command line invocation
> like:
> 
>     echo "i 0x4914 e" > /dev/pcan0
> 
> For this reason it is important to create the chardev-device-entries,
> too. If your target does no create the device files automatically with
> UDEV you have to run with the script
> 
>     ./pcan_make_devices 2
> 
> even if only the netdev driver is used.
> 
> ---
> 
> Indeed i was already thinking about the integration of the netlink-based
> configuration interface (of the mainline kernel) into the PCAN driver.
> 
> But finally this would be another add-on ... IMHO the better approach would be
> to support the PEAK hardware in the form of mainline drivers, like we already
> have for the PCAN PCI and PCAN ISA hardware. A future PCAN USB driver could be
> created on the basis of the existing USB CAN adapter from ESD and EMS.
> 
> Best regards,
> Oliver
> --
> To unsubscribe from this list: send the line "unsubscribe linux-can" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: Bit rate configuration of PEAK USB devices

[Heinz-Jürgen Oertel]

On 15.11.2011 19:33, Oliver Hartkopp wrote:

> I forgot to mention that you can also use the PCAN ioctl() interface on the
> PEAK chardevices or their pcanlib ...
>

Danke Oliver,

for now I decided to use something like

system("echo \"i 0x4914 e\" > /dev/pcan0");

Unfortunately at the moment I have  no idea how to determine if I'm just talking to an Peak or an EMS interface  to select the method of setting the bit rate.

 Regards
 Heinz

Re: Bit rate configuration of PEAK USB devices

[Kurt Van Dijck]

On Thu, Nov 17, 2011 at 07:49:43AM +0100, Heinz-Jürgen Oertel wrote:
> 
> Danke Oliver,
> 
> for now I decided to use something like
> 
> system("echo \"i 0x4914 e\" > /dev/pcan0");
> 
> Unfortunately at the moment I have  no idea how to determine if I'm just talking to an Peak or an EMS interface  to select the method of setting the bit rate.

Maybe

$ ip -d link show can0

will show differently?

Regards
Kurt
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Re: Bit rate configuration of PEAK USB devices

[Oliver Hartkopp]

On 17.11.2011 12:24, Kurt Van Dijck wrote:

> On Thu, Nov 17, 2011 at 07:49:43AM +0100, Heinz-Jürgen Oertel wrote:
>>
>> Danke Oliver,
>>
>> for now I decided to use something like
>>
>> system("echo \"i 0x4914 e\" > /dev/pcan0");
>>
>> Unfortunately at the moment I have  no idea how to determine if I'm just talking to an Peak or an EMS interface  to select the method of setting the bit rate.
> 
> Maybe
> 
> $ ip -d link show can0
> 
> will show differently?


No.

The PEAK driver does not use the candev framework (drivers/net/can/dev.c).
Therefore you won't see anything beyond up/down state and tx_queue_len, etc.
Not bitrate settings :-(

Regards,
Oliver
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Re: Bit rate configuration of PEAK USB devices

[Kurt Van Dijck]

On Thu, Nov 17, 2011 at 05:14:33PM +0100, Oliver Hartkopp wrote:
> On 17.11.2011 12:24, Kurt Van Dijck wrote:
> 
> > On Thu, Nov 17, 2011 at 07:49:43AM +0100, Heinz-Jürgen Oertel wrote:
> >>
> >> Danke Oliver,
> >>
> >> for now I decided to use something like
> >>
> >> system("echo \"i 0x4914 e\" > /dev/pcan0");
> >>
> >> Unfortunately at the moment I have  no idea how to determine if I'm just talking to an Peak or an EMS interface  to select the method of setting the bit rate.
> > 
> > Maybe
> > 
> > $ ip -d link show can0
> > 
> > will show differently?
> 
> 
> No.
> 
> The PEAK driver does not use the candev framework (drivers/net/can/dev.c).
> Therefore you won't see anything beyond up/down state and tx_queue_len, etc.
> Not bitrate settings :-(
My idea was to use this 'lack of information' to auto-decide if it's an EMS or PEAK
interface. But Heinz-Jürgen already pointed out that using some /proc file, you
can also see if a device is a PEAK device.

Kurt
> 
> Regards,
> Oliver
> --
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Re: Bit rate configuration of PEAK USB devices

[Wolfgang Grandegger]

On 11/17/2011 05:25 PM, Kurt Van Dijck wrote:
> On Thu, Nov 17, 2011 at 05:14:33PM +0100, Oliver Hartkopp wrote:
>> On 17.11.2011 12:24, Kurt Van Dijck wrote:
>>
>>> On Thu, Nov 17, 2011 at 07:49:43AM +0100, Heinz-Jürgen Oertel wrote:
>>>>
>>>> Danke Oliver,
>>>>
>>>> for now I decided to use something like
>>>>
>>>> system("echo \"i 0x4914 e\" > /dev/pcan0");
>>>>
>>>> Unfortunately at the moment I have  no idea how to determine if I'm just talking to an Peak or an EMS interface  to select the method of setting the bit rate.
>>>
>>> Maybe
>>>
>>> $ ip -d link show can0
>>>
>>> will show differently?
>>
>>
>> No.
>>
>> The PEAK driver does not use the candev framework (drivers/net/can/dev.c).
>> Therefore you won't see anything beyond up/down state and tx_queue_len, etc.
>> Not bitrate settings :-(
> My idea was to use this 'lack of information' to auto-decide if it's an EMS or PEAK
> interface. But Heinz-Jürgen already pointed out that using some /proc file, you
> can also see if a device is a PEAK device.

The best solution would be to provide a *real* Socket-CAN driver for the
PEAK USB devices instead of continuing with this mixed net-char-dev
crap. Well, it does work basically but it's not what users nowadays want.

Wolfgang.

Re: Bit rate configuration of PEAK USB devices

[Marc Kleine-Budde]

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On 11/17/2011 06:55 PM, Wolfgang Grandegger wrote:
> The best solution would be to provide a *real* Socket-CAN driver for the
> PEAK USB devices instead of continuing with this mixed net-char-dev
> crap. Well, it does work basically but it's not what users nowadays want.

Full ACK. Can someone put people at peak on Cc?

Marc

-- 
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Re: Bit rate configuration of PEAK USB devices

[Oliver Hartkopp]

On 17.11.2011 07:49, Heinz-Jürgen Oertel wrote:

> 
> On 15.11.2011 19:33, Oliver Hartkopp wrote:
> 
>> I forgot to mention that you can also use the PCAN ioctl() interface on the
>> PEAK chardevices or their pcanlib ...
>>
> 
> Danke Oliver,
> 
> for now I decided to use something like
> 
> system("echo \"i 0x4914 e\" > /dev/pcan0");
> 
> Unfortunately at the moment I have  no idea how to determine if I'm just talking to an Peak or an EMS interface  to select the method of setting the bit rate.


An idea is to write different udev rules due to the different USB Vendor IDs,
that do the initialization in different manners.

If you want to set the default bitrate for all PEAK devices, you can set the
global default bitrate on the module commandline.

Regards,
Oliver