On Sat, Oct 11, 2014 at 01:37:56AM +0530, Sumit Semwal wrote: > Devices sharing buffers using dma-buf could benefit from sharing their > constraints via struct device, and dma-buf framework would manage the > common constraints for all attached devices per buffer. > > With that information, we could have a 'generic' allocator helper in > the form of a central dma-buf exporter, which can create dma-bufs, and > allocate backing storage at the time of first call to > dma_buf_map_attachment. > > This allocation would utilise the constraint-mask by matching it to > the right allocator from a pool of allocators, and then allocating > buffer backing storage from this allocator. > > The pool of allocators could be platform-dependent, allowing for > platforms to hide the specifics of these allocators from the devices > that access the dma-buf buffers. > > A sample sequence could be: > - get handle to cenalloc_device, > - create a dmabuf using cenalloc_buffer_create; > - use this dmabuf to attach each device, which has its constraints > set in the constraints mask (dev->dma_params->access_constraints_mask) > - at each dma_buf_attach() call, dma-buf will check to see if the constraint > mask for the device requesting attachment is compatible with the > constraints > of devices already attached to the dma-buf; returns an error if it isn't. > - after all devices have attached, the first call to dma_buf_map_attachment() > will allocate the backing storage for the buffer. > - follow the dma-buf api for map / unmap etc usage. > - detach all attachments, > - call cenalloc_buffer_free to free the buffer if refcount reaches zero; > > ** IMPORTANT** > This mechanism of delayed allocation based on constraint-enablement will work > *ONLY IF* the first map_attachment() call is made AFTER all attach() calls are > done. > > Signed-off-by: Sumit Semwal <sumit.semwal at linaro.org> > Cc: linux-kernel at vger.kernel.org > Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org> > Cc: linux-media at vger.kernel.org > Cc: dri-devel at lists.freedesktop.org > Cc: linaro-mm-sig at lists.linaro.org > --- > MAINTAINERS | 1 + > drivers/cenalloc/cenalloc.c | 597 > +++++++++++++++++++++++++++++++++++++++ > drivers/cenalloc/cenalloc.h | 99 +++++++ > drivers/cenalloc/cenalloc_priv.h | 188 ++++++++++++ > 4 files changed, 885 insertions(+) > create mode 100644 drivers/cenalloc/cenalloc.c > create mode 100644 drivers/cenalloc/cenalloc.h > create mode 100644 drivers/cenalloc/cenalloc_priv.h > > diff --git a/MAINTAINERS b/MAINTAINERS > index 40d4796..e88ac81 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -3039,6 +3039,7 @@ L: linux-media at vger.kernel.org > L: dri-devel at lists.freedesktop.org > L: linaro-mm-sig at lists.linaro.org > F: drivers/dma-buf/ > +F: drivers/cenalloc/ > F: include/linux/dma-buf* > F: include/linux/reservation.h > F: include/linux/*fence.h > diff --git a/drivers/cenalloc/cenalloc.c b/drivers/cenalloc/cenalloc.c > new file mode 100644 > index 0000000..f278056 > --- /dev/null > +++ b/drivers/cenalloc/cenalloc.c > @@ -0,0 +1,597 @@ > +/* > + * Allocator helper framework for constraints-aware dma-buf backing storage > + * allocation. > + * This allows constraint-sharing devices to deferred-allocate buffers shared > + * via dma-buf. > + * > + * Copyright(C) 2014 Linaro Limited. All rights reserved. > + * Author: Sumit Semwal <sumit.semwal at linaro.org> > + * > + * Structure for management of clients, buffers etc heavily derived from > + * Android's ION framework.
Does that mean we can drop ION after this gets merged? /me dreams Anyway, why a new directory? Why not just put it in drivers/dma-buf ? Or a subdir below there? thanks, greg k-h
