On Tue, Jun 10, 2025 at 06:12:28AM -0700, Jared Kangas wrote: > Hi all, > > This patch series is based on a previous discussion around CMA heap > naming. [1] The heap's name depends on the device name, which is > generally "reserved", "linux,cma", or "default-pool", but could be any > arbitrary name given to the default CMA area in the devicetree. For a > consistent userspace interface, the series introduces a constant name > for the CMA heap, and for backwards compatibility, an additional Kconfig > that controls the creation of a legacy-named heap with the same CMA > backing. > > The ideas to handle backwards compatibility in [1] are to either use a > symlink or add a heap node with a duplicate minor. However, I assume > that we don't want to create symlinks in /dev from module initcalls, and > attempting to duplicate minors would cause device_create() to fail. > Because of these drawbacks, after brainstorming with Maxime Ripard, I > went with creating a new node in devtmpfs with its own minor. This > admittedly makes it a little unclear that the old and new nodes are > backed by the same heap when both are present. The only approach that I > think would provide total clarity on this in userspace is symlinking, > which seemed like a fairly involved solution for devtmpfs, but if I'm > wrong on this, please let me know. > > Changelog: > > v4: > - Fix ERR_PTR() usage for negative return value. > > v3: > - Extract documentation markup fix to separate patch. > - Adjust DEFAULT_CMA_NAME per discussion in [2]. > - Warn if the legacy heap name and the default heap name are the same. > - Fix DMABUF_HEAPS_CMA_LEGACY prompt. > - Touch up commit log wording. > > v2: > - Use tabs instead of spaces for large vertical alignment. > > [1]: https://lore.kernel.org/all/f6412229-4606-41ad-8c05-7bbba2eb6...@ti.com/ > [2]: > https://lore.kernel.org/all/CANDhNCroe6ZBtN_o=c71kzffawk-ff5rcdnr9p5h1sgpows...@mail.gmail.com/ > > Jared Kangas (3): > Documentation: dma-buf: heaps: Fix code markup > dma-buf: heaps: Parameterize heap name in __add_cma_heap() > dma-buf: heaps: Give default CMA heap a fixed name > > Documentation/userspace-api/dma-buf-heaps.rst | 11 +++--- > drivers/dma-buf/heaps/Kconfig | 10 ++++++ > drivers/dma-buf/heaps/cma_heap.c | 36 +++++++++++++++---- > 3 files changed, 46 insertions(+), 11 deletions(-) > > -- > 2.49.0 >
Hi Sumit, Just wanted to check in on this since discussion has died down this iteration: what's the status on this series? If there's anything I can do to help, I'm happy to lend a hand. Thanks, Jared
