Le mardi 31 juillet 2012 19:28:12 Laurent Pinchart, vous avez écrit : > Hi Rémi, > > On Tuesday 31 July 2012 16:39:00 Rémi Denis-Courmont wrote: > > Le mardi 31 juillet 2012 14:56:14 Laurent Pinchart, vous avez écrit : > > > > For that matter, wouldn't it be useful to support exporting a userptr > > > > buffer at some point in the future? > > > > > > Shouldn't USERPTR usage be discouraged once we get dma-buf support ? > > > > USERPTR, where available, is currently the only way to perform zero-copy > > from kernel to userspace. READWRITE does not support zero-copy at all. > > MMAP only supports zero-copy if userspace knows a boundary on the number > > of concurrent buffers *and* the device can deal with that number of > > buffers; in general, MMAP requires memory copying. > > Could you please share your use case(s) with us ? I want to receive the video buffers in user space for processing. Typically "processing" is software encoding or conversion. That's what virtually any V4L application does on the desktop... -- Rémi Denis-Courmont http://www.remlab.net/ http://fi.linkedin.com/in/remidenis -- 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
