> Mauro Carvalho Chehab [mailto:mchehab@xxxxxxxxxx] wrote: > >Pawel Osciak wrote: >> Hi, >> >>> Aguirre, Sergio wrote: >>> Basically, when calling VIDIOC_REQBUFS with a certain buffer >>> Count, we had a software limit for total size, calculated depending on: >>> >>> Total bytesize = bytesperline x height x count >>> >>> So, we had an arbitrary limit to, say 32 MB, which was generic. >>> >>> Now, we want to condition it ONLY when MMAP buffers will be used. >>> Meaning, we don't want to keep that policy when the kernel is not >>> allocating the space >>> >>> But the thing is that, according to videobuf documentation, buf_setup is >>> the one who should put a RAM usage limit. BUT the memory type passed to >>> reqbufs is not propagated to buf_setup, therefore forcing me to go to a >>> non-standard memory limitation in my reqbufs callback function, instead >>> of doing it properly inside buf_setup. >> >> buf_setup is called during REQBUFS and is indeed the place to limit the >> size and actually allocate the buffers as well, or at least try to do so, >> as V4L2 API requires. This is not currently the case with videobuf, but >> right now we are working to change it. > >I can't see the problem you're mentioning. Drivers apply (or should apply) >the maximum size limit at buffer setup. For example bttv driver seems to do >the right thing: Not really a problem. You are right about setup. I meant that videobuf behaves differently in regard to when it actually allocates the 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
