[U-Boot] Running mx6qsabrelite at 1Gz with Freescale kernel rel_imx_3.0.35_4.1.0

[Thierry Bultel <tbultel@free.fr>]

Le 18/03/2014 13:34, Stefano Babic a ?crit :
> Hi Thierry,
>
>
> On 18/03/2014 12:28, tbultel at free.fr wrote:
>>
>> Hi,
>>
>> I am working on a board (AMOS820 from Via) based on the mx6qsabrelite.
>>
>> The BSP provided by the manufacturer is quite old.
>> I managed to port it from Freescale uboot-imx rel_imx_3.0.35_4.1.0 to u-boot
>> mainline, and basically the latest issue I have is the cpu frequency.
>>
>> The kernel I use is the rel_imx_3.0.35_4.1.0 as well (same tag name)
>>
>> With the old u-boot, it runs at 1Ghz because the BSP explicitly has a call to
>>
>> clk_config(CONFIG_REF_CLK_FREQ, 1000, CPU_CLK);
>>
>> With the new u-boot, it runs at default freq which is 800Mhz (at least, what I
>> guess from the Bogomips because no other log says it)
> It is can taken as reference, but checking the BogoMIPS is not the right
> way to proof it. You should take a look at the CCM registers when Linux
> is running ( CCM_ANALOG_PLL_ARM).
>
>> I have attempted to pass "arm_freq=1000" to the boot args but that does not
>> change anything.
> Well, this is a kernel issue, and related to an ancient version.
>
>> My concern is that clk_config does not seem to be available anymore, there is
>> get_mcu_main_clk but no set routine.
> It was never available in mainline.
>
>> I wonder if it is intentional, I could write a set routine but I wonder if it
>> could be accepted as a patch.
> Why not ? All patches are discussed here and if it makes sense to merge
> it, it will be merged.

Hi Stefano,
many thanks for your advice,

It is now running at 1Ghz. I still have a couple of issues that prevent me to submit
a patch as is:

1) The kernel (old, I know) I am using does not like that PCIe to have been formerly probed by
u-boot. It hangs at probing if so.
Thus I have to patch my kernel, or add an environment variable to not initialize PCIe when
set, in order to keep compatible with old kernels. For now, in order to boot, I have
temporary disabled PCIe support in U-boot.

2) The splashscreen (loaded at 10000000) disappears when loading the kernel
Would you have any idea or hints about it ?

Best Regards
Thierry



> Best regards,
> Stefano Babic
>