Hi Lee, I was browsing the mailing-list archive and found your email about the issue with DIB0700-based devices on an NSLU2. I myself use a Terratec Cinergy DT XS Diversity which I think had the same issue as you described it. I found that the cause was the rather big DMA buffer of 39480 bytes as specified in dib0700_devices.c. Looking at the kernel's arch/arm/mach-ixp4xx/common-pci.c there is a top limit of 4096 bytes for a DMA buffer set by the function call dmabounce_register_dev(dev, 2048, 4096); My recipe (for SlugOS) below changes the big buffer to a smaller one and also increases the number of buffers (not sure if the latter is really needed). Now the module is working just fine, even recording on both adapters gives a CPU usage of just ~25%. So the smaller buffer size does not seem to hurt at all. Not sure why it is needed in the first place. Bye, -Thomas PS: My recipe "v4l-dvb_0776e4801991.bb" ========= CUT ========== DESCRIPTION = "v4l-dvb modules" #SECTION = "" PRIORITY = "optional" HOMEPAGE = "http://linuxtv.org/"; LICENSE = "GPL" DEPENDS = "virtual/kernel" PR = "r0" SRC_URI = "http://linuxtv.org/hg/v4l-dvb/archive/${PV}.tar.bz2"; S = "${WORKDIR}/${PN}-${PV}" inherit module MAKE_TARGETS = "DIR=${STAGING_KERNEL_DIR}" do_configure() { # fix make target cd "${S}" sed -i 's%^install:%install modules_install:%' Makefile # reduce buffer size (ixp4xx can handle only <= 4096 # (see arch/arm/mach-ixp4xx/common-pci.c) cd "${S}/linux/drivers/media/dvb/dvb-usb" sed -i 's%buffersize = 39480%buffersize = 4096%' dib0700_devices.c sed -i 's%\.count = 4,%.count = 7,%' dib0700_devices.c # do not strip here cd "${S}/v4l/scripts" sed -i 's%@strip %@#strip %' make_makefile.pl } fakeroot do_install() { oe_runmake DESTDIR="${D}" install } FILES_${PN} = "/lib/modules" ========= CUT ========== ---- Original Message ---- From: Lee Essen lee.essen at nowonline.co.uk Date: Thu Apr 3 12:48:05 CEST 2008 Hi, Apologies if this is directed in the wrong place, as I suspect this is more of a kernel/USB issue than a DVB driver issue, but it does have an impact on people wanting to use this device with an NSLU2 (and I suspect it will also be a problem with many other devices.) I have been experimenting using a variety of DVB-T USB devices with an NSLU2 with my ultimate aim being to build in a dual DVB-T device into the case and use it in very much the same way as the HDHomeRun device. Using a DTT200U based device everything worked perfectly. Then I started playing with a DIB0700 based device (actually an Elgato Eye-TV Diversity) and the system would just hang whenever I started using dvbstream, I got slightly different behaviour if I tried to tune it to an invalid frequency and eventually managed to get to a state when I could interrupt it before it completely locked up. It seems that the driver was flagging an issue in the ARM architecture around not calling dma_free_coherent() with IRQ's disabled, apparently a warning was recently added to the ARM kernel so it logs a message and a stack trace each time ... this seemed to be happening so frequently it effectively locked the system up. I did a little digging, but I'm not a kernel expert at all, and it seems that the ehci_hcd module is actually where the call is originating rather than the DVB driver itself, so I suspect that this will actually effect a significant number of the drivers when used on an ARM platform. For the purposes of testing I removed the warning (from arch/arm/mm/ consistent line 363) and everything is fine, the driver operates perfectly and I can stream video nicely. BUT - clearly there is some kind of issue here that needs to be resolved. More information is available at the link below, and also I have read comments suggesting that the issue has been discussed on the arm-kernel mailing list but that no resolution has yet been found. http://forum.soft32.com/linux/ehci_hcd-map_single-unable-map-unsafe-buffer-standard-NSLU2-ftopict461241.html For reference I'm using 2.6.24 and have tried the most recent drivers from linuxtv.org as well as a variety of others -- all seem to have the same problem (which is expected if the problem is actually in the USB system.) Hope this is useful, Lee. _______________________________________________ linux-dvb mailing list linux-dvb@xxxxxxxxxxx http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb
