Hi Rémi, On Tuesday 31 July 2012 21:39:40 Rémi Denis-Courmont wrote: > Le mardi 31 juillet 2012 19:28:12 Laurent Pinchart, vous avez écrit : > > 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... But what prevents you from using MMAP ? -- Regards, Laurent Pinchart -- 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
