[linux-dvb] Possible SMP problems with budget_av/saa7134

[Oliver Endriss]

Matthias Dahl wrote:
> Hello all.
> 
> I am resending the following message because I didn't get any response so far 
> and in addition I am putting it on cc' to the vdr devel list. I'd look into 
> this issue myself, yet I don't have the necessary time to dive into the DVB 
> tree. So please, if anyone knows how to debug this or has any hint where the 
> problem could be located... I'd be more than grateful to hear about it.
> 
> By the way, just today after a few minutes of uptime with vdr 1.7.0, I got 
> those (increased the CAM check interval to 5 seconds btw):
> 
> vdr: [3280] ERROR: can't write to CI adapter on device 0: Input/output error
> vdr: [3280] ERROR: can't write to CI adapter on device 0: Invalid argument
> 
> And the CAM stopped working until I restarted vdr. In one forum post someone 
> reported about similar problems with MythTV, so it's becoming more and more 
> likely that this is indeed a problem within the dvb tree. And if it's a SMP 
> problem, it should get fixed because multicore systems will be everywhere 
> pretty soon.
> 
> Thanks again.
> 
> ----------------------------------------------------------------------------------
> 
> Hello all.
> 
> After minutes or hours or days of running vdr 1.4.7, I get the following 
> messages in my syslog: 
> 
>    dvb_ca adapter 0: CAM tried to send a buffer larger than the ecount size!
>    dvb_ca adapter 0: DVB CAM link initialisation failed :(
> 
> When running vdr 1.6.x, the problems are even more frequent/worse and I get
> those:
> 
>   dvb_ca adapter 0: CAM tried to send a buffer larger than the link buffer
>   size (192 > 128)!
>   vdr: [3140] ERROR: can't write to CI adapter on device 0: Input/output error
>   dvb_ca adapter 0: CAM tried to send a buffer larger than the ecount size!
>   dvb_ca adapter 0: DVB CAM link initialisation failed :(
> 
> The result is always the same, the CAM stops decrypting and I have to restart 
> vdr. After a lot of searching around, I've learnt that I am not the only one 
> with those problems and they seem to be related to multi core systems. I read 
> that pining vdr down to one CPU core might help... and indeed it did.
> 
> This cannot be a hardware related issue because...
> 
>  1) meanwhile I switched from a NForce 590 SLI to a X48 chipset and thus also
>     from an AMD64 X2 5600+ (Winchester) to an Intel Core2Duo E8400 (Wolfdale)
> 
>  2) I swapped my KNC One DVB-C Plus for a new one
> 
> And the problems persist.
> 
> I've already written a report to the vdr list which was unfortunately ignored 
> and besides it looks more like a dvb issue itself.
> 
> I was unable to test the kernel with nosmp or similar (which was reported by 
> others to work just fine) because I need this machine to work on.
> 
> I've attached detailed informations about my system and I'd be more than happy 
> to help fix this once and for all, so one can savely rely on vdr again.
> 
> Last but not least, I am using a AlphaCrypt Light module with 3.15 firmware.
> 
> Thanks a lot in advance for every help.
> 
> Best regards,
> Matthias Dahl

Please test the attached patch (untested because I do not own this kind
of hardware). Please save your work before loading the patched driver,
since a locking bug might crash your machine...

CU
Oliver

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