Re: [ivtv-devel] [patch] Fix DMA TIMEOUT lockups (for me at least, for the last 26 hours)
On Friday 27 July 2007 16:00, Mark Bryars wrote: I already posted this patch yesterday but it was a hand crafted patch, so I'm resubmitting it properly with my latest results: Attached is the patch against 2.6.22.1 sources which I have been testing against 13 WinTV PVR-150 cards and 1 WinTV PVR-500, over the last 26 hours I have had no DMA TIMEOUTs, when normally I would have had 6 or 7. In my testing the cards also recover from a DMA TIMEOUT if you provoke one setting a stupidly low latency. You may also need Hans's VBI/PCM patch that is attached for convenience. Please report back on any successes/failures/side effects of this fix to the list. Regards, Mark Bryars Thanks for your work on this. I never made the relationship between DMA size and DMA TIMEOUTs. A very quick test yesterday suggested that this might indeed be the cause of the problems. What I want to figure out today is whether the gather-scatter DMA is indeed the problem and if replacing it with multiple 'simple' DMA calls will also fix the problem. The reason is that allocating large buffers increases the chance that the buffer allocations will fail. Kernel allocation of large buffers is not recommended. Also, if the bitrate is increased to the maximum then a buffer size of 0x2 is probably not sufficient either. Thanks, Hans ___ ivtv-devel mailing list ivtv-devel@ivtvdriver.org http://ivtvdriver.org/mailman/listinfo/ivtv-devel
Re: [ivtv-devel] [patch] Fix DMA TIMEOUT lockups (for me at least, for the last 26 hours)
On Saturday 28 July 2007 12:35, Hans Verkuil wrote: On Friday 27 July 2007 16:00, Mark Bryars wrote: I already posted this patch yesterday but it was a hand crafted patch, so I'm resubmitting it properly with my latest results: Attached is the patch against 2.6.22.1 sources which I have been testing against 13 WinTV PVR-150 cards and 1 WinTV PVR-500, over the last 26 hours I have had no DMA TIMEOUTs, when normally I would have had 6 or 7. In my testing the cards also recover from a DMA TIMEOUT if you provoke one setting a stupidly low latency. You may also need Hans's VBI/PCM patch that is attached for convenience. Please report back on any successes/failures/side effects of this fix to the list. Regards, Mark Bryars Thanks for your work on this. I never made the relationship between DMA size and DMA TIMEOUTs. A very quick test yesterday suggested that this might indeed be the cause of the problems. What I want to figure out today is whether the gather-scatter DMA is indeed the problem and if replacing it with multiple 'simple' DMA calls will also fix the problem. The reason is that allocating large buffers increases the chance that the buffer allocations will fail. Kernel allocation of large buffers is not recommended. Also, if the bitrate is increased to the maximum then a buffer size of 0x2 is probably not sufficient either. Preliminary results strongly suggest that it is indeed scatter/gather DMA that the card's DMA engine chokes on. If I handle this from within the driver as multiple single DMA transfers then everything seems to work. Mark, very nice work! I never linked the large DMA transfers with the DMA timeouts. Thanks, Hans ___ ivtv-devel mailing list ivtv-devel@ivtvdriver.org http://ivtvdriver.org/mailman/listinfo/ivtv-devel
Re: [ivtv-devel] [patch] Fix DMA TIMEOUT lockups (for me at least, for the last 26 hours)
It appears the 128K buffer can not allocate at least in my 64 bit kernel but the 64K buffer allocates fine and when I then limit my transfers to 64K. I get lots of warnings and video artifacts: Ok, setting the buffer size to 0x1F000 and limiting transfers to 0x1F000 seems to work for me. I am currently displaying both tuners at the same time using mplayer and it appears that all is well. In the past I was forced to use PIO with the older PVR250 as it had serious problems with dma. After 10 minutes I am not calling this one fixed but it looks promising. John ___ ivtv-devel mailing list ivtv-devel@ivtvdriver.org http://ivtvdriver.org/mailman/listinfo/ivtv-devel
