18 Jun

MythTV / PVR-350 Card Troubles, IRQs and Resourse Units

It remains to be seen if this will change anything, but things will be better now Just Because.  At lunchtime, I moved the PVR-350 to a different PCI slot.  When I started all of this, I slapped it in the top slot, mainly because there were dongles slotted in the middle two.  In this case, the two were a slot-mounted Video Out connector and a Coaxial Audio connector for the motherboard.

This board is the A7N8X-VM from Asus.  An older board, but nothing really wrong with it (that a CMOS battery wouldn’t fix, anyway).  It has an 8X AGP slot and three PCI slots.

Well, here’s a little blast from the past with which you may not be familiar.  I don’t know how manufacturers do it now, but motherboards with any age on them use what a Tyan tech once described to me as “Resourse Units” to assign IRQ addresses.  In this case, the AGP and the PCI slot next to it share an IRQ, the two middle PCI slots have individual (non-shared) IRQs, and the final PCI slot shares it’s IRQ with the USB subsystem.  This isn’t a problem with a modern operating system.

However, I’m thinking that my onboard “AGP” video uses the same IRQ as that top PCI slot.  The same slot that my PVR-350 was in.  I don’t know if that is causing any of the issues, but it certainly isn’t good practice.