Re: HauppaugeTV-quadHD DVB-T mpeg risc op code error

[Sean Young <sean@mess.org>]

On Tue, Apr 28, 2020 at 08:24:20PM +0200, Martin Burnicki wrote:
> Hi,
> 
> Am 27.04.20 um 10:59 schrieb Martin Burnicki:
> > Sean Young wrote:
> >> Would you mind testing this patch please?
> > 
> > I'm going to try it this evening.
> > 
> > I'll have to find out how to do an out-of-tree build for a copy of the
> > cx module that includes the patch.
> > 
> > My own kernel driver is always and only built out-of-tree, but for the
> > cx driver I need to see which files I need to copy to a local directory,
> > and if there is anything else that needs to be done to build a copy of
> > it out-of-tree.
> 
> Sorry, I haven't managed to test the patch, yet.
> 
> Currently I have the driver loaded with
> 
> options cx23885 dma_reset_workaround=2
> 
> but today there were 3 occurrences of the risc opcode error:
> 
> root@pc:~# dmesg | grep risc
> [166528.023263] cx23885: cx23885[0]: mpeg risc op code error
> [166528.023273] cx23885: cx23885[0]:   cmds: init risc lo   : 0xff667000
> [166528.023277] cx23885: cx23885[0]:   cmds: init risc hi   : 0x00000000
> [166528.023293] cx23885: cx23885[0]:   cmds: risc pc lo     : 0xff667018
> [166528.023296] cx23885: cx23885[0]:   cmds: risc pc hi     : 0x00000000
> [166528.023319] cx23885: cx23885[0]:   risc0:
> [166528.023324] cx23885: cx23885[0]:   risc1:
> [166528.023330] cx23885: cx23885[0]:   risc2:
> [166528.023334] cx23885: cx23885[0]:   risc3:
> [180595.947077] cx23885: cx23885[0]: mpeg risc op code error
> [180595.947087] cx23885: cx23885[0]:   cmds: init risc lo   : 0xfc6ee000
> [180595.947090] cx23885: cx23885[0]:   cmds: init risc hi   : 0x00000000
> [180595.947107] cx23885: cx23885[0]:   cmds: risc pc lo     : 0xfc6ee018
> [180595.947110] cx23885: cx23885[0]:   cmds: risc pc hi     : 0x00000000
> [180595.947133] cx23885: cx23885[0]:   risc0:
> [180595.947138] cx23885: cx23885[0]:   risc1:
> [180595.947143] cx23885: cx23885[0]:   risc2:
> [180595.947147] cx23885: cx23885[0]:   risc3:
> [180595.947263] cx23885: cx23885[0]: mpeg risc op code error
> [180595.947270] cx23885: cx23885[0]:   cmds: init risc lo   : 0xfc6ee000
> [180595.947274] cx23885: cx23885[0]:   cmds: init risc hi   : 0x00000000
> [180595.947290] cx23885: cx23885[0]:   cmds: risc pc lo     : 0xfc6ee018
> [180595.947293] cx23885: cx23885[0]:   cmds: risc pc hi     : 0x00000000
> [180595.947315] cx23885: cx23885[0]:   risc0:
> [180595.947319] cx23885: cx23885[0]:   risc1:
> [180595.947324] cx23885: cx23885[0]:   risc2:
> [180595.947328] cx23885: cx23885[0]:   risc3:
> 
> My wife is very happy that the recordings of the TV shows she wanted to
> see later were aborted. ;-)

Drats.

> So the workaround doesn't seem to fix the problem anyway, and the patch
> would just enable the workaround with out the specific option, right?

Yes, that's right.

> The effect of the workaround looks just like debug levels lower than 7,
> it just seems to reduce the probability that the bug occurs, but doesn't
> really fix it.
> 
> So my conclusion is still that that this smells like a missing memory
> barrier or so in the driver.
> 
> Since the driver seems to work properly with older mainboards/CPU types,
> this doesn't sound like a problem in the CX chip, IMO.

I would agree with that. I would suspect same issue was being papered over
by the patch; now what that issue is, I don't know. Certainly some ordering
or barrier issue seems likely.

Actually I suspected this all along, but the workaround is the best we have.

I think, some time spent hunting down the issue would really be helpful
here. Hopefully that doesn't mean too many aborted recordings..

Thanks,

Sean