Re: [Linux1394-devel] updated dma to user space API
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From: Sebastien R. <Seb...@sy...> - 2000-04-25 23:20:47
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>>>>> "Jun" == Jun Sun <jul...@ya...> writes: >> NOTE 1: the driver is probably not safe for SMP machines (will do that >> later). It might also not be wise to share the device /dev/ohci1394 between >> several threads/processes. >> Jun> I am lost a little bit. How does this driver relate to libraw? The direct dma to user space feature bypass libraw (at least for the moment). So you use libraw to send 1394 commands to your camera, and you use the /dev/ohci1394 device to initialize/receive video frames. Jun> If the answer is yes, I wonder if any behavior is modified. For example, Jun> if both processes listen for the same iso channel, will they both get the Jun> data? If you use libraw to get iso data, then I guess yes data are duplicated. For direct iso-dma to user space, no. A same Iso channel cannot be listened by two separate dma contexts (except if you have 2 cards in the box I think), so there can be only one destination in memory for one iso channel. -- Sebastien Rougeaux RSISE, The Australian National University |