From 849369d6c66d3054688672f97d31fceb8e8230fb Mon Sep 17 00:00:00 2001 From: root Date: Fri, 25 Dec 2015 04:40:36 +0000 Subject: initial_commit --- Documentation/video4linux/bttv/README.freeze | 74 ++++++++++++++++++++++++++++ 1 file changed, 74 insertions(+) create mode 100644 Documentation/video4linux/bttv/README.freeze (limited to 'Documentation/video4linux/bttv/README.freeze') diff --git a/Documentation/video4linux/bttv/README.freeze b/Documentation/video4linux/bttv/README.freeze new file mode 100644 index 00000000..5eddfa07 --- /dev/null +++ b/Documentation/video4linux/bttv/README.freeze @@ -0,0 +1,74 @@ + +If the box freezes hard with bttv ... +===================================== + +It might be a bttv driver bug. It also might be bad hardware. It also +might be something else ... + +Just mailing me "bttv freezes" isn't going to help much. This README +has a few hints how you can help to pin down the problem. + + +bttv bugs +--------- + +If some version works and another doesn't it is likely to be a driver +bug. It is very helpful if you can tell where exactly it broke +(i.e. the last working and the first broken version). + +With a hard freeze you probably doesn't find anything in the logfiles. +The only way to capture any kernel messages is to hook up a serial +console and let some terminal application log the messages. /me uses +screen. See Documentation/serial-console.txt for details on setting +up a serial console. + +Read Documentation/oops-tracing.txt to learn how to get any useful +information out of a register+stack dump printed by the kernel on +protection faults (so-called "kernel oops"). + +If you run into some kind of deadlock, you can try to dump a call trace +for each process using sysrq-t (see Documentation/sysrq.txt). +This way it is possible to figure where *exactly* some process in "D" +state is stuck. + +I've seen reports that bttv 0.7.x crashes whereas 0.8.x works rock solid +for some people. Thus probably a small buglet left somewhere in bttv +0.7.x. I have no idea where exactly, it works stable for me and a lot of +other people. But in case you have problems with the 0.7.x versions you +can give 0.8.x a try ... + + +hardware bugs +------------- + +Some hardware can't deal with PCI-PCI transfers (i.e. grabber => vga). +Sometimes problems show up with bttv just because of the high load on +the PCI bus. The bt848/878 chips have a few workarounds for known +incompatibilities, see README.quirks. + +Some folks report that increasing the pci latency helps too, +althrought I'm not sure whenever this really fixes the problems or +only makes it less likely to happen. Both bttv and btaudio have a +insmod option to set the PCI latency of the device. + +Some mainboard have problems to deal correctly with multiple devices +doing DMA at the same time. bttv + ide seems to cause this sometimes, +if this is the case you likely see freezes only with video and hard disk +access at the same time. Updating the IDE driver to get the latest and +greatest workarounds for hardware bugs might fix these problems. + + +other +----- + +If you use some binary-only yunk (like nvidia module) try to reproduce +the problem without. + +IRQ sharing is known to cause problems in some cases. It works just +fine in theory and many configurations. Neverless it might be worth a +try to shuffle around the PCI cards to give bttv another IRQ or make +it share the IRQ with some other piece of hardware. IRQ sharing with +VGA cards seems to cause trouble sometimes. I've also seen funny +effects with bttv sharing the IRQ with the ACPI bridge (and +apci-enabled kernel). + -- cgit v1.2.3