After the last round submitting the system-uncached heap, I got some feedback that Daniel would like to see it demonstrated with a mesa based system. I'm still working on such a gralloc implementation (using the db845c), but along with other work, so I don't yet have something to share there.
However, Bing Song reached out and was interested in having a uncached variant for the CMA heap as well, and he shared this patch providing an initial implementation.
This gave me some hesitation with regards to the earlier discussion around what sort of attributes would be useful for the flags field of the allocation IOCTL.
In earlier discussions, folks seemed happy to provide the uncached system heap functionality as its own heap chardev, as it seemed uncertain that the uncached attribute would truely be generic across all heaps.
But with Bing's patch, it seems like it may be generically useful, and utilizing a flag might be a bit cleaner then adding lots of duplicative heap names postfixed with "-uncached".
So I wanted to re-submit both of these together to reopen that discussion on the question of if a BUF_FLAG_UNCACHED flag would make sense, or if folks still think separate heap chardevs is the way to go.
thanks -john
Cc: Daniel Vetter daniel@ffwll.ch Cc: Sumit Semwal sumit.semwal@linaro.org Cc: Liam Mark lmark@codeaurora.org Cc: Laura Abbott labbott@kernel.org Cc: Brian Starkey Brian.Starkey@arm.com Cc: Hridya Valsaraju hridya@google.com Cc: Suren Baghdasaryan surenb@google.com Cc: Sandeep Patil sspatil@google.com Cc: Daniel Mentz danielmentz@google.com Cc: Chris Goldsworthy cgoldswo@codeaurora.org Cc: Ørjan Eide orjan.eide@arm.com Cc: Robin Murphy robin.murphy@arm.com Cc: Ezequiel Garcia ezequiel@collabora.com Cc: Simon Ser contact@emersion.fr Cc: James Jones jajones@nvidia.com Cc: Bing Song bing.song@nxp.com Cc: linux-media@vger.kernel.org Cc: dri-devel@lists.freedesktop.org
Bing Song (1): dma-buf: cma_heap: Add a cma-uncached heap re-using the cma heap
John Stultz (2): dma-buf: dma-heap: Keep track of the heap device struct dma-buf: system_heap: Add a system-uncached heap re-using the system heap
drivers/dma-buf/dma-heap.c | 33 ++++++-- drivers/dma-buf/heaps/cma_heap.c | 119 +++++++++++++++++++++++++--- drivers/dma-buf/heaps/system_heap.c | 111 ++++++++++++++++++++++---- include/linux/dma-heap.h | 9 +++ 4 files changed, 236 insertions(+), 36 deletions(-)