Il 03/02/2012 00:12, Devin Heitmueller ha scritto: > On Thu, Feb 2, 2012 at 6:06 PM, Gianluca Gennari <gennarone@xxxxxxxxx> wrote: >> Il 02/02/2012 20:07, Devin Heitmueller ha scritto: >> Hi Devin, >> thanks for the explanation. The CPU is MIPS based (not ARM) but I guess >> there is not much of a difference from this point of view. >> As I mentioned in my first reply, I never had this kind of errors when I >> was using a dvb-usb USB stick. Now I'm trying to replicate the problem >> with a Terratec Hybrid XS (em28xx-dvb + zl10353 + xc2028), and so far >> I've stressed it for a few hours without problems. We will see in a day >> or two if I can make it fail in the same way. > > I'm pretty sure this will happen under MIPS as well. That said, you > will typically hit this condition if you stop streaming and then > restart it several hours into operation. In other words, make sure > you're not just watching/streaming video for a few hours and thinking > you're stressing the particular use case. You need to stop/start to > hit it. Yes, I've been switching between the mediaplayer (playing some 1080p mkv file to stress the memory) and the USB tuner, but so far so good. But I need to run the test longer to draw some conclusion. > I haven't looked that closely at dvb_usb's memory allocation strategy. > Perhaps it allocates the memory up front, or perhaps it doesn't > demand coherent memory (something which will work on x86 and maybe > MIPS, but will cause an immediate panic on ARM). > > I've run into this issue myself on an embedded target with em28xx and > ARM. I plan on hacking a fix to statically allocate the buffers at > driver init, but I cannot imagine that being a change that would be > accepted into the upstream kernel. If you have some patch that you want to share, I will be happy to test it. > It probably makes sense to figure out whether MIPS requires coherent > memory like ARM does. If it doesn't then you can probably just hack > your copy of the em28xx driver to not ask for coherent memory. If it > does require coherent memory, then you'll probably need to allocate > the memory up front. > Interesting suggestion. I have really no idea if MIPS really requires coherent memory in this case. I may try to hack it and see what happens. Thank you very much for the detailed explanation. Regards, Gianluca > Cheers, > > Devin > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
