[linux-dvb] PCI latency for Aver761 / dvb-bt8xx / FDSR overflows

[Hamish Moffatt <hamish@cloud.net.au>]

Hi,

I've been having a lot of trouble with FBUS & FDSR interrupts on the
Avermedia 761 (dvb-bt8xx card). Sometimes I get just one FBUS error
at a time, which the data sheet indicates is a buffer overflow caused by
long bus latencies. Usually these correspond to first starting to watch
live TV or record something in MythTV.

Sometimes this turns into a storm of FDSR interrupts, and eventually I
get an IRQ lockup message. At this point I never receive any more data
on the demux device until I reload the driver.

Sep 19 21:35:06 tv kernel: bt878(0): irq FBUS risc_pc=1fa12080
Sep 19 22:05:51 tv kernel: bt878(0): irq FBUS risc_pc=1fa12178
Sep 19 22:49:02 tv kernel: bt878(0): irq FBUS risc_pc=1fa120f8
Sep 20 18:44:03 tv kernel: bt878(0): irq FBUS risc_pc=1fa12178
Sep 20 19:30:08 tv kernel: bt878(0): irq FBUS risc_pc=1fa12100
Sep 20 19:30:08 tv kernel: bt878(0): irq FBUS risc_pc=1fa12188
Sep 20 19:30:08 tv kernel: bt878(0): irq FBUS risc_pc=1fa12210
Sep 20 19:30:08 tv kernel: bt878(0): irq FDSR FBUS risc_pc=1fa12210
Sep 20 19:30:08 tv last message repeated 70 times
Sep 20 19:30:08 tv kernel: bt878(0): IRQ lockup, cleared int mask

I've been increasing the PCI bus latency timer on the bt878 (audio and
video sections) gradually to try to kick this problem. I've been running
with 166 (= ~5478us) for a while and this still happens. I've just
increased it to 192 (~6336us) to see if that helps. 

The other devices on that PCI bus are the other DVB card (budget-ci
driver), which was also starting a recording at about 19:30 when the
lockup occurred, an rtl8029 network card (typically inactive),
and an SB Live (not used). I've had the other DVB card's latency set to
the same value, though now I've left it at 166 rather than increasing it
like the Aver.

Can anyone else who's running the Aver761 successfully tell me if they
have tweaked the PCI latency for it, and if so what value did you find
helpful?

Is there anything we can do the driver to have it recover from this
condition?

Thanks

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