[Xenomai] SPI tx underflow interrupt not available

Gilles Chanteperdrix gilles.chanteperdrix at xenomai.org
Tue Aug 26 22:29:33 CEST 2014

On 08/26/2014 04:24 PM, Reitinger, Peter wrote:
> Dear Xenomai people,
> I am currently trying to write an SPI slave rtdm driver with fifo and dma support. I would like to receive an interrupt if there is an underflow in the tx fifo.
> Therefore I try to request the related hardware interrupt (which is irq 125 at my emtrion board which has EDMA and 2 McSPI interfaces where I am trying McSPI1).

Are you sure the irq number is 125? If 125 is a "physical" irq number,
it is almost probably not the number you should pass to
rtdm_irq_request. Have you tried requesting it as a Linux interrupt?

> Unfortunately it seems that interrupt 125 is reserved by another linux
driver because a list of /proc/irq/125 shows:
> root at dimm-am335x:/proc# ls /proc/irq/125
> 53100000.sham  spurious

Have you tried grepping "sham" in the kernel sources?


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