Hello, I put Lee in CC. Thomas Reitmayr a écrit : > 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. > Well, I experienced the same issue with the Terratec Cinergy Hybrid XS. See the problem on the em28xx ML: http://www.spinics.net/lists/linux-usb-devel/msg09511.html This problem can occur generally on USB devices on the ixp4xx arch. I tried to patch the linux kernel for the dma part of ixp4xx: http://www.spinics.net/lists/arm-kernel/msg43509.html With this patch the driver was able to tune channels instead of the famous BUG message. But I could not stream video unfortunately. So this patch did not have any following although I expected someone to propose something better. Your solution is to decrease the buffer size and I suspect other USB drivers made a similar correction. > Bye, > -Thomas Cheers, Thierry > > > 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 > _______________________________________________ linux-dvb mailing list linux-dvb@xxxxxxxxxxx http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb
