Re: [PATCH 2/4] can: flexcan: add hardware controller version support

[Marc Kleine-Budde <mkl@pengutronix.de>]

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On 06/27/2012 11:43 AM, Wolfgang Grandegger wrote:
> Hi Marc,
> 
> On 06/27/2012 10:56 AM, Wolfgang Grandegger wrote:
>> On 06/27/2012 10:27 AM, Marc Kleine-Budde wrote:
>>> On 06/27/2012 10:19 AM, Hui Wang wrote:
>>>> At least in the i.MX series, the flexcan contrller divides into ver_3
>>>> and ver_10, current driver is for ver_3 controller.
>>>>
>>>> i.MX6 has ver_10 controller, it has more reigsters than ver_3 has.
>>>> The rxfgmask (Rx FIFO Global Mask) register is one of the new added.
>>>> Its reset value is 0xffffffff, this means ID Filter Table must be
>>>> checked when receive a packet, but the driver is designed to accept
>>>> everything during the chip start, we need to clear this register to
>>>> follow this design.
>>>>
>>>> Add a hw_ver entry in the device tree, this can let us distinguish
>>>> which version the controller is, if we don't set value to this entry,
>>>> the hw_ver is 3 by default, this is backward compatible for existing
>>>> platforms like powerpc and imx35.
>>>
>>> Is it possible to read this value from the hardware?
>>> Another possibility would be to introduce a new compatible device in the
>>> device tree.
>>
>> I vote for the latter. IIRC, in the past we already had some discussion
>> on how to handle version dependent Flexcan hardware, e.g. by using
>> flexcan-vX.X or being expicit using fsl,p1010-flexcan. Search for "Add
>> support for powerpc" in the netdev mailing list. I added the
>> devicetree-discuss ml for that reason.
> 
> I looked up the threads and found:
> 
>   http://marc.info/?w=4&r=1&s=Fix+up+fsl-flexcan+device+tree+bi&q=t
> 
> In the Flexcan driver we currently only have:
> 
>   static struct of_device_id flexcan_of_match[] = {
>         {
>                 .compatible = "fsl,p1010-flexcan",
>         },
>         {},
>   };
> 
> What compatible string do they actually use for the i.MX6Q board? Shawn
> or Hui? We need to fix that. From the discussion mentioned above I think
> "fsl,flexcan-v10" would be acceptable. Unfortunately, we do not known

As far as I understand the DT, the name should be something like

"fsl,${OLDEST_SOCK_THAT_HAS_THIS_VERSION_OF_FLEXCAN}-flexcan".

> the internal version of the Flexcan controllers used in the various
> PowerPC and ARM SOCs. We already realized some differences with
> interrupts and bus error handling between i.MX28 and i.MX35. Would be
> nice if someone (from Freescale?) could finally clarify that.

That information would be interesting.

Marc
-- 
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