Hi Andy, On Tuesday 08 March 2011 15:01:10 Andy Walls wrote: > On Tue, 2011-03-08 at 09:13 +0100, Hans Verkuil wrote: > > Hi all, > > > > We had a discussion yesterday regarding ways in which linaro can assist > > V4L2 development. One topic was that of sorting out memory providers like > > GEM and HWMEM. > > > > Today I learned of yet another one: UMP from ARM. > > > > http://blogs.arm.com/multimedia/249-making-the-mali-gpu-device-driver-ope > > n-source/page__cid__133__show__newcomment/ > > > > This is getting out of hand. I think that organizing a meeting to solve > > this mess should be on the top of the list. Companies keep on solving > > the same problem time and again and since none of it enters the mainline > > kernel any driver using it is also impossible to upstream. > > > > All these memory-related modules have the same purpose: make it possible > > to allocate/reserve large amounts of memory and share it between > > different subsystems (primarily framebuffer, GPU and V4L). [snip] > > It really shouldn't be that hard to get everyone involved together and > > settle on a single solution (either based on an existing proposal or > > create a 'the best of' vendor-neutral solution). > > "Single" might be making the problem impossibly hard to solve well. > One-size-fits-all solutions have a tendency to fall short on meeting > someone's critical requirement. I will agree that "less than n", for > some small n, is certainly desirable. > > The memory allocators and managers are ideally satisfying the > requirements imposed by device hardware, what userspace applications are > expected to do with the buffers, and system performance. (And maybe the > platform architecture, I/O bus, and dedicated video memory?) In the embedded world, a very common use case is to capture video data from an ISP (V4L2+MC), process it in a DSP (V4L2+M2M, tidspbridge, ...) and display it on the GPU (OpenGL/ES). We need to be able to share a data buffer between the ISP and the DSP, and another buffer between the DSP and the GPU. If processing is not required, sharing a data buffer between the ISP and the GPU is required. Achieving zero-copy requires a single memory management solution used by the ISP, the DSP and the GPU. -- 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
