Should the number in /proc/interrupts for empeg_rdsirq be this high on a machine with no tuner (and without a Hijack fake tuner)?

0: 4 empeg_state
1: 0 empeg_usbirq
2: 0 empeg_cs4231
3: 22678580 empeg_rdsirq
4: 3358446 empeg_input
6: 36298 ide0
7: 27438 SMC9194
17: 140 serial
20: 729948 audio-empeg
26: 1906854 timer
FIQ: cs4231dma

It's rising more rapidly than any of the other lines - over 1000 per second. It makes no difference whether the player is paused or running.

Looking at /proc/empeg_rds gives just the single line

Log:

which doesn't seem exceptionally helpful.

Is this normal? Can anyone explain it all?

It's normal, you should get 1087 per second. The DSP outputs an RDS data clock (which we interrupt on) whether or not it is actually receiving anything. The IRQ handler is pretty low overhead & so can be safely ignored, generally.

Hugo

Ah, understood. I now have a little more knowledge than before. Thanks, Hugo.