[linux-dvb] bt878(0): IRQ lockup, cleared int mask

Hamish Moffatt hamish at cloud.net.au
Sun Jul 31 15:19:21 CEST 2005

On Sun, Jul 31, 2005 at 02:08:08PM +0100, David Johnson wrote:
> On Sunday 31 July 2005 04:05, Jukka Tastula wrote:
> > On Sunday 31 July 2005 00:17, David Johnson wrote:
> > > As I'm watching TV, I'm getting lots of the following messages in demsg:
> > > bt878(0): irq FDSR FBUS risc_pc=1fc66010
> > > bt878(0): irq FBUS risc_pc=1fc66158
> > > bt878(0): IRQ lockup, cleared int mask
> >
> > I had exact same problem for a very long time with my nxt6000 nebula. I
> > finally some weeks ago tracked it down to the nic I was using (rtl8139).
> I've tracked down the cause on my system - it generates irq messages every 
> time the disk (an SATA drive using the sata_nv driver) is accessed. Accessing 
> a large file makes the card die much quicker than it otherwise would.

I had the same problem. As soon as I started using the SATA controller
(which in my case was not sata_nv but one of the SIL drivers), I had
trouble with the BT878.

Getting errors was as simple as

tzap -r 'some channel' &
cat /dev/dvb/adapter0/dvr0 > /path/to/sata/disk/file

> So this makes the card last longer before dying, but it still dies after 120 
> errors. I suppose I could just comment out that section of code completely, 
> but there's still something causing this problem and it would be much better 
> to track it down and fix it rather than just hide it.

In my opinion the FIFO in the BT878 is simply not big enough for this
application. It is designed for carrying audio data at up to 1Mbit,
not DVB-T data at up to 23Mbit or more.

I replaced the card with a CX2388x-based card and I've never had an
issue since.

You might have some luck adjusting the PCI latencies using setpci,
powertweak etc. I never did though.

Hamish Moffatt VK3SB <hamish at debian.org> <hamish at cloud.net.au>

More information about the linux-dvb mailing list