Re: [Xenomai] Xenomai on Atmel SAMA5D3 with a 3.14 kernel

[Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>]

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On 06/10/2014 10:19 AM, Maxime Ripard wrote:
> On Fri, Jun 06, 2014 at 07:52:13PM +0200, Gilles Chanteperdrix
> wrote:
>> On 06/06/2014 03:59 PM, Maxime Ripard wrote:
>>> Hi Gilles,
>>> 
>>> I've been experimenting these days with the i-pipe 3.14
>>> kernel, and current xenomai master branch on the Atmel SAMA5D3
>>> SoC.
>>> 
>>> There's a few issues there, the first one being that 
>>> at91_ipipe_early_init crashes because of a NULL pointer 
>>> dereference. This is due to the clk_get_rate call on the clock
>>>  returned by clk_get(NULL, "mck").
>>> 
>>> This clk_get call cannot since 3.14 because the clock code has 
>>> been rewritten, and you can't use clkdev anymore.
>> 
>> Well, it works on AT91. (RM9200 and SMA9263). What you are doing
>> with SAMA5D3 here is actually a port to a new platform.
> 
> Not really. The SAMA5D3 is the latest evolution of the AT91, and
> the only major difference is that it's now using a Cortex-A5, but
> it's mostly the same.
> 
> The only major difference I can find is that like all the recent
> AT91 SoCs, it's using the common clock framework in Linux, while
> the 9200 and the 9263 are still using the old API.

What I mean is that from the I-pipe patch point of view, this is a new
processor, and you should not presume too much. Also note that since
3.14, the I-pipe patch uses the atmel tclib
(drivers/misc/atmel_tclib.c), which uses clk_get and friends, so, if
clk_get does not work for this new processor, the tclib will not work
either.


- -- 
                                                                Gilles.
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