660cd44659
[WHY] 1. Drivers using DRM_GEM_SHADOW_PLANE_HELPER_FUNCS and DRM_GEM_SHMEM_DRIVER_OPS (e.g., udl, ast) do not require sg_table import. They only need dma_buf_vmap() to access the shared buffer's kernel virtual address. 2. On certain Aspeed-based boards, a dma_mask of 0xffff_ffff may trigger SWIOTLB during dmabuf import. However, IO_TLB_SEGSIZE restricts the maximum DMA streaming mapping memory, resulting in errors like: ast 0000:07:00.0: swiotlb buffer is full (sz: 3145728 bytes), total 32768 (slots), used 0 (slots) [HOW] Provide a gem_prime_import implementation without sg_table mapping to avoid issues (e.g., "swiotlb buffer is full"). Drivers that do not require sg_table can adopt this. Signed-off-by: Shixiong Ou <oushixiong@kylinos.cn> Acked-by: Thomas Zimmermann <tzimmermann@suse.de> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de> Link: https://lore.kernel.org/r/20250522070714.439824-1-oushixiong1025@163.com
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.