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. 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. 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. Cheers, Devin -- Devin J. Heitmueller - Kernel Labs http://www.kernellabs.com -- 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
