Re: iMX6Q Linux 3.10.17 Trying to read registers at boot time

[jose <jose.ferreiro@horus.es>]

Thanks Eric

El 28/01/2015 a las 11:29, Eric Bénard escribió:
> Hi Jose,
>
> Le Wed, 28 Jan 2015 11:00:40 +0100,
> Jose Mª Ferreriro Carnota<jose.ferreiro@horus.es>  a écrit :
>> I was derived here from :
>> https://community.freescale.com/message/473511#473511
>>
>> My kernel stops loading when I try to access to registers in
>> mach-imx6q.c. I think it has something to do with iMX6 security system.
>> Access to that registers at that moment seems to be denied and the
>> kernel load crashes.
>>
> you code is wrong : you can't access the physical memory as there is
> MMU. You can check in the code how this is done.
>
> The following link may me also be of interest :
> http://www.makelinux.net/ldd3/chp-9-sect-4
>
> meta-fsl-arm is not the right place for this kind of generic
> kernel question, you should ask on kernel related mailing lists such as
> for ARM :
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> for beginners :
> http://kernelnewbies.org/ML
>
> Best regards
> Eric

I used the request_mem_region, ioremap and ioread32 process  .. and 
kernel keeps hanging if I try to use the ioread32 funtion.

Then I traced calls to __request_region on kernel/resource.c. IPU driver 
is calling this in a different way:

   platform_get_resource(pdev, IORESOURCE_MEM, 0);

   devm_request_mem_region(&pdev->dev, res->start, resource_size(res), 
pdev->name);

I am going to redirect this to linux-arm-kernel and see if I can use 
this other method.

Best regards,
Jose