[Xenomai] Only 2 serial ports at a time with xeno_16550A driver

Greg Gallagher greg at embeddedgreg.com
Tue May 22 20:38:47 CEST 2018


This is highly likely, I'm not sure when this driver was last tested.
Are you able to put a patch together?  Has anyone else sense similar
behaviour?

-Greg

On Tue, May 22, 2018 at 2:31 PM, C Smith <csmithquestions at gmail.com> wrote:
> I think I may have found a bug in the rtl_16550A driver when using shared
> interrupts. (I am on Xenomai 2.6.5. Kernel 3.18.20.)
>
> I think the interrupt handler is not sending an EOI to the lower (ISA 8259)
> interrupt controller, though it certainly is doing the right thing for
> higher IRQs above 16.
>
> I used a Moxa 4-port serial card in the PCI bus which has all 4 ports
> sharing IRQ 17. The rtl_16550A driver can use all 4 ports OK.
>
> But the rtl_16550A driver stalls after one interrupt when I use multiple
> serial ports on my motherboard where all the serial ports share IRQ 5. This
> is indicated by the fact that I can send one byte out the port, or I can
> get a single byte into the port, before the port can no longer send or
> receive anything further.
>
> I diffed the Xenomai 3.0.5 source versus the 2.6.5 rtl_16550A.c source and
> the code is very similar so the liability is in both branches I assume.
>
> -C Smith
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