Re: 3.10.9-rt5 with Atmel AT91SAM9G25 SoC triggers "Trying to free already-free IRQ 1"

[Sebastian Andrzej Siewior <bigeasy@linutronix.de>]

* Sami Pietikäinen | 2013-10-14 07:24:20 [+0000]:

>Hello Sebastian
Hello Sami,

>>The problem does not look -RT specific.
>
>I would say that at least the "Trying to free already-free IRQ 1" warning is somehow -RT specific. When I tested the 3.6.9 kernel without the RT patch there were no warnings (using SAMA5D35). The same warning Michael is having appeared only after applying the patch. However, the other problems Michael is having might also be something else.
>
>>I don't understand why uart tries over and over to request that interrupt but it simply doesn't work.
>>I am a little confused why at91 is having everything (or more than one
>>device) is on irq 16. It should have only one device on each interrupt since they have usually dedicated irq lines.
>
>arm-at91-tclib-default-to-tclib-timer-for-rt.patch has the following comment:
>"RT is not too happy about the shared timer interrupt in AT91
>devices. Default to tclib timer for RT."
>
>Snippet from SAMA5D35 datasheet:
>"Usually, the Debug Unit interrupt line connects to the interrupt source 1 of the AIC, which may be shared with the real-time clock, the system timer interrupt lines and other system peripheral interrupts"
>
>The debug unit also has UART which is probably Michael's ttyS0.

Argh. I missed that detail. So that explains why UART and the timer
share the same interrupt number. Is that timer really disabled in your
config?

>
>BR,
>Sami

Sebastian
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