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Message-ID: <CAO_48GFy4xD+mS_1YBfpQ5Q9eBBjBDz_VxZ+8hXKLwVPARY+ig@mail.gmail.com> Date: Tue, 14 Oct 2014 19:33:10 +0530 From: Sumit Semwal <sumit.semwal@...aro.org> To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Sumit Semwal <sumit.semwal@...aro.org>, Linaro MM SIG <linaro-mm-sig@...ts.linaro.org>, linaro-kernel@...ts.linaro.org, LKML <linux-kernel@...r.kernel.org>, DRI mailing list <dri-devel@...ts.freedesktop.org>, "linux-media@...r.kernel.org" <linux-media@...r.kernel.org> Subject: Re: [RFC 2/4] cenalloc: Constraint-Enabled Allocation helpers for dma-buf Hi Greg, Daniel! On 12 October 2014 00:10, Daniel Vetter <daniel@...ll.ch> wrote: > 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@...aro.org> >> > Cc: linux-kernel@...r.kernel.org >> > Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org> >> > Cc: linux-media@...r.kernel.org >> > Cc: dri-devel@...ts.freedesktop.org >> > Cc: linaro-mm-sig@...ts.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@...r.kernel.org >> > L: dri-devel@...ts.freedesktop.org >> > L: linaro-mm-sig@...ts.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@...aro.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? > > Yeah, I hope so. Not sure whetether this hope is shared by google android > people ... Apologies for the delay in response; was travelling for LPC and so couldn't respond. Yes, that is certainly the hope, but this is the first-step RFC which would need a few more things before ION can be replaced completely. > >> /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 -- Thanks and regards, Sumit Semwal Kernel Team Lead - Linaro Mobile Group Linaro.org │ Open source software for ARM SoCs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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