On 07/03/2014 11:09 AM, Dong Aisheng wrote:

On Thu, Jul 03, 2014 at 11:04:36AM +0200, Marc Kleine-Budde wrote:

quoted

On 07/03/2014 10:48 AM, Dong Aisheng wrote:

quoted

On Thu, Jul 03, 2014 at 09:12:49AM +0200, Marc Kleine-Budde wrote:

quoted

On 07/03/2014 05:48 AM, Dong Aisheng wrote:

quoted

On Wed, Jul 02, 2014 at 09:13:07PM +0200, Marc Kleine-Budde wrote:

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On 07/02/2014 07:54 PM, Oliver Hartkopp wrote:

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I'm not really familiar with the naming concept in device trees.

What is your opinion about the remarks below?

The entries in the DT, at least on freescale baords, follow the naming
scheme of the reference manual. E.g. on the mx25 it's can1 and can2:

    can1: can@43f88000 { ... }
    can2: can@43f8c000 { ... }

And on the mx28, its:

    can0: can@80032000 { ... }
    can1: can@80034000 { ... }

Because the imx25 datasheet uses a "1" based counting scheme, while the
imx28 uses a "0" based one.

So it's best practise to follow the naming and numbering scheme of the
hardware reference manual.....and if you have access to the
documentation of the m_can core, use clock names of the m_can core for
the clock-names property.

Based on my knowledge, device tree allows define phandle name according to
the real device name of HW according spec while the device node name should
be general(e.g can@80032000 rather than flexcan@80032000).
For imx6sx, there are already following entries in
arch/arm/boot/dts/imx6sx.dtsi
flexcan1: can@02090000 {...}
flexcan2: can@02094000 {...}
So i'd prefer to define as:
m_can1: canfd@020e8000 {...}
m_can2: canfd@020f0000 {...}


One problem is there're can alias already.
aliases {
	can0 = &flexcan1;
	can1 = &flexcan2;
	...
}
I'm not sure adding can2&can3 for mcan is properly:
aliases {
	can0 = &flexcan1;
	can1 = &flexcan2;
	can2 = &m_can1;
	can3 = &m_can2;
	...
}
Since the m_can driver does not need to use aliases,
so i will not add them.

IMHO It's fine too add the can{2,3} aliases to m_can, too.

I think the main problem for doing this way is that the meaning of id
return by of_alias_get_id may be not persistent.
e.g
For MX6SX
aliases {
	can0 = &flexcan1;
	can1 = &flexcan2;
	can2 = &m_can1;
	can3 = &m_can2;
	...
}

For other platform, it could be:
aliases {
	can0 = &m_can1;
	can1 = &m_can2;
	...
}
It's hard for driver to use.

The driver doesn't make use of it, does it?

quoted

And actually the M_CAN driver does not need to use the alias.
So i wonder if it makes sense to add the alias for m_can devices
like that.

For example the imx53 has two different SPI units, in the alias section
we see:

                spi0 = &ecspi1;
                spi1 = &ecspi2;
                spi2 = &cspi;

Thanks for the info.
I'm not clear what's our purpose adding alias like this?
Can you help explain it a bit?

You can use the alias in your dts to refer to the node instead of the
more complicate name. Further you bring a order to all devices of the
same type and you can make use of the number in the alias for other
purposes, which is however not used for CAN afaik.

Do we need adding alias for all exist devices?

Have a look at the existing imx*.dtsi files. If there are already
aliases for a given device type, then it makes sense to add new devices
of that type to the alias aswell.

Marc

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