Arunpravin Paneer Selvam 97ff194625 drm/amdgpu: Implement a new userqueue fence driver
Developed a userqueue fence driver for the userqueue process shared
BO synchronization.

Create a dma fence having write pointer as the seqno and allocate a
seq64 memory for each user queue process and feed this memory address
into the firmware/hardware, thus the firmware writes the read pointer
into the given address when the process completes it execution.
Compare wptr and rptr, if rptr >= wptr, signal the fences for the waiting
process to consume the buffers.

v2: Worked on review comments from Christian for the following
    modifications

    - Add wptr as sequence number into the fence
    - Add a reference count for the fence driver
    - Add dma_fence_put below the list_del as it might
      frees the userq fence.
    - Trim unnecessary code in interrupt handler.
    - Check dma fence signaled state in dma fence creation
      function for a potential problem of hardware completing
      the job processing beforehand.
    - Add necessary locks.
    - Create a list and process all the unsignaled fences.
    - clean up fences in destroy function.
    - implement .signaled callback function

v3: Worked on review comments from Christian
    - Modify naming convention for reference counted objects
    - Fix fence driver reference drop issue
    - Drop amdgpu_userq_fence_driver_process() function return value

v4: Worked on review comments from Christian
    - Moved fence driver allocation into amdgpu_userq_fence_driver_alloc()
    - Added detail doc mentioning the differences b/w
      two spinlocks declared.

v5: Worked on review comments from Christian
    - Check before upcast and remove local variable
    - Add error handling in fence_drv alloc function.
    - Move rptr read fn outside of the loop and remove WARN_ON in
      destroy function.

v6:
  - clear the seq64 memory in user fence driver(Christian)
  - fix for the wptr va bo mapping(Christian)
  - move the fence_drv xa entry erase code from the interrupt handler
    into user fence destroy function

Signed-off-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Suggested-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
2025-04-08 16:48:16 -04:00
2024-09-01 20:43:24 -07:00
2025-02-04 11:27:45 -05:00
2022-09-28 09:02:20 +02:00
2025-03-09 13:45:25 -10:00
2024-03-18 03:36:32 -06:00

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.
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