sleep time is doubled, xilinx_zynq_zedboard

[Gedare Bloom]

On Thu, May 1, 2014 at 9:01 AM, Giovanni Macciocu <G.Macciocu at sron.nl> wrote:
>  Yes I've noticed the same thing.
>
> The ARM documentation states the following:
>
> PERIPHCLK must be synchronous with CLK, and the PERIPHCLK clock period,
> N, must be configured as a multiple of the CLK clock period. This
> multiple N must be equal to, or greater than two.
> (http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0407f/CJHIGGDG.html)
>
> So yes I think in this case the the multiple N = 2, resulting in a
> peripheral bus clocked on half the speed. I would say this is a bug in
> the xilinx_zynq_zedboard BSP,
> the default value in configure.ac is 666666667U which can never be the
> case as this is the CPU speed.
>
That definitely sounds like a bug in the zedboard BSP then. Although
setting the BSPOPT is a suitable workaround, if 333 MHz is the correct
peripheral clock speed for the zedboard then it should be made the
default value.

> This still doens't solve the problem related to the serial port dough.
> I've rolled back to an rtems head of +/- half a year ago. There my
> serial port does work with a baudrate at 11500, i haven't been able to
> tacke the difference.
>
You may be interested to try to use git-bisect to find the commit
where the buadrate changes. Depending how long it takes for you to
figure out the effective baudrate, git-bisect should get you to the
bad commit in reasonable time.

> Regards,
>
> Giovanni
>
>>>> Thomas Doerfler <Thomas.Doerfler at embedded-brains.de> 5/1/2014 2:38
> PM >>>
> Giovanni,
>
> without knowing the BSP: You are talking about CPU clock, the macro is
> call Periphclk. Can it be that the peripheral bus is clocked with half
> of the CPU frequency?
>
> wkr,
>
> Thomas.
>
> Am 01.05.2014 12:52, schrieb Giovanni Macciocu:
>> I've made some tests by changing the value of
> BSP_ARM_A9MPCORE_PERIPHCLK.
>> The value should be 666666667U as this is my cpu clock speed.
>>
>> However in the following cases
>>
>> #define BSP_ARM_A9MPCORE_PERIPHCLK (2 * 666666667U)
>>
>> --> a Sleep now takes 4 times as long
>>
>> #define BSP_ARM_A9MPCORE_PERIPHCLK 2 (666666667U / 2)
>>
>> --> The sleep is now correct
>>
>> In all cases the serial port keeps working at half of the normal
> buadrate.
>>
>> Regards,
>>
>> Giovanni
>>
>>
>>>>> "Giovanni Macciocu" <G.Macciocu at sron.nl> 5/1/2014 10:53 AM >>>
>> In my bspopt.h
>>
>> /* ARM Cortex-A9 MPCore PERIPHCLK clock frequency in Hz */
>> #define BSP_ARM_A9MPCORE_PERIPHCLK 666666667U
>>
>> This is the correct processor speed for my platform.
>>
>>>>> Chris Johns <chrisj at rtems.org> 5/1/2014 10:24 AM >>>
>> t you take a look at the BSPOPTS for the zync BSP. There are
>> some clocks you can set and one of these may help. I think
>> BSP_ARM_A9MPCORE_PERIPHCLK is the one.
>>
>> Chris
>>
>>
>>
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>
>
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