On Fri, Oct 10, 2014 at 04:09:00PM -0700, Greg Kroah-Hartman wrote: > 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@xxxxxxxxxx> > > Cc: linux-kernel@xxxxxxxxxxxxxxx > > Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > > Cc: linux-media@xxxxxxxxxxxxxxx > > Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx > > Cc: linaro-mm-sig@xxxxxxxxxxxxxxxx > > --- > > 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@xxxxxxxxxxxxxxx > > L: dri-devel@xxxxxxxxxxxxxxxxxxxxx > > L: linaro-mm-sig@xxxxxxxxxxxxxxxx > > 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@xxxxxxxxxx> > > + * > > + * 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? Yeah, I hope so. Not sure whetether this hope is shared by google android people ... > /me dreams I guess we can collectively dream about this next week at plumbers ;-) I'll try to squeeze in some light review of Sumit's patches between conference travels ... Cheers, Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch -- 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
