On Wed, May 25, 2022 at 1:07 AM Richard Weinberger <richard.weinber...@gmail.com> wrote: > > On Wed, May 25, 2022 at 2:18 AM C Smith via Xenomai <xenomai@xenomai.org> > wrote: > > We are using Xenomai 3.1.2 on kernel 4.19.229, X86 CPU > > We have a (Moxa CP-104ul) serial card on an isolated PCI bus interrupt 17. > > lspci -v confirms that the serial card is isolated and that no other > > peripheral uses this interrupt. > > > > We have the 16550A serial driver loaded, and an external serial device > > trying to initiate a serial connection, but no interrupts are being > > generated. The interrupt counter in /proc/xenomai/irq stay at 0. > > > > [user@device~]$ cat /proc/xenomai/irq > > IRQ CPU0 CPU1 CPU2 CPU3 > > 17: 0 0 0 0 rtser2 > > rtser3 rtser4 rtser5 > > > > As an experiment: if we enable the Azalia sound chip in the BIOS, and > > load its Alsa sound driver, the Serial card will then share IRQ 17 > > with that sound chip, and then the serial card works. The serial > > interrupt counter is incrementing in /proc/xenomai/irq and our serial > > peripheral can utilize the serial port OK. > > I think enabling it in the BIOS is the key. Can you try keeping the sound > driver > disabled and only enable in the BIOS.
We left the Azalia sound chip enabled in the BIOS, and disabled the sound driver. Interrupts in /proc/xenomai/irq are still not incrementing when serial packets come into the po > > We don't want the sound driver enabled, but this test indicates that > > 16550A somehow failed to enable its interrupt, whereas the sound > > driver succeeded in doing so. > > > > How can we check a PIC, etc. to verify that the serial interrupt is > > truly enabled when the 16550A driver is loaded alone? > > You can enable CONFIG_GENERIC_IRQ_DEBUGFS and then poke into > /sys/kernel/debug/irq/. > > -- > Thanks, > //richard We rebuilt our kernel with CONFIG_GENERIC_IRQ_DEBUGFS enabled, booted with the sound driver disabled and loaded xeno_16550A: [root@device~]# cat /sys/kernel/debug/irq/irqs/17 cat: /sys/kernel/debug/irq/irqs/17: No such file or directory. We noticed that /proc/xenomai/irq is not showing IRQ17 immediately after xeno_16550A is loaded. proc/xenomai/irq only shows IRQ17 after the serial device is opened for the first time. So /sys/kernel/debug/irq/irqs/17 doesn't become available until the sound driver is loaded. We also have a (Peak) CAN card installed in this system, and the corresponding IRQ shows up immediately in /sys/kernel/debug/irq/irqs/18 after the xeno_can driver is loaded. Should we expect to see the IRQ show up in /proc/xenomai/irq immediately after loading the xeno_16550A driver? How can we debug this further, since /sys/kernel/debug/irq/irqs/17 does not exist without that sound driver?
