Hi Mauro, thank you for your reply. On Tuesday, October 27, 2009 1:36 PM Mauro Carvalho Chehab [mailto:mchehab@xxxxxxxxxxxxx] wrote: >> could anybody confirm that there is no full/working support for USERPTR in >> current videobuf-core? That is the conclusion I came up with after a more >> thorough investigation. >> >> I am currently working to fix that, and will hopefully be posting patches in >> the coming days/weeks. Is there any other development effort underway related >> to this problem? > > (...) >The last time I tested the support for userptr at videobuf-core, it were >working on x86 plataforms. On that time, I used vivi with videobuf-dma-sg >for such tests (it were before its conversion to use videobuf-vmalloc). >As support for userptr on videobuf-vmalloc is missing, vivi can't be used >for such tests anymore (a good contribution would be to add userptr support >on videobuf-vmalloc). I might be missing something, but for me the path looks as follows (sources: kernel, LWN articles, V4L2 API Specification): 1. open, query, format, other stuff, unimportant 2. VIDEOBUF_REQBUFS - pass type and set memory to V4L2_MEMORY_USERPTR only. 3. VIDEOBUF_QUERYBUFS - only for memory-mapped I/O, so not called. 4. VIDEOBUF_QBUF - pass type, memory, userptr and length fields only. As the API Specification states in section 3.3: "No buffers are allocated beforehands, consequently they are not indexed and cannot be queried like mapped buffers with the VIDIOC_QUERYBUF ioctl." But when one calls QBUF, videobuf_qbuf() uses b->index for all types of memory. I have found no mention in the API Specs about passing/returning indexes in USERPTR, quite the contrary, they actually state that indexes are not used in that mode for neither REQBUFS nor QBUF at all. Even if that was the case though, would an application be supposed to arbitrarily choose what index to pass? If so, how would it know what range is valid? And even if it would, the next check: (buf->state != VIDEOBUF_NEEDS_INIT && buf_state != VIDEOBUF_IDLE) would most probably fail anyway. How to enqueue and handle multiple userptr buffers? Best regards -- Pawel Osciak Linux Platform Group Samsung Poland R&D Center -- 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
