drm/i915: Multi-BB execbuf
Allow multiple batch buffers to be submitted in a single execbuf IOCTL after a context has been configured with the 'set_parallel' extension. The number batches is implicit based on the contexts configuration. This is implemented with a series of loops. First a loop is used to find all the batches, a loop to pin all the HW contexts, a loop to create all the requests, a loop to submit (emit BB start, etc...) all the requests, a loop to tie the requests to the VMAs they touch, and finally a loop to commit the requests to the backend. A composite fence is also created for the generated requests to return to the user and to stick in dma resv slots. No behavior from the existing IOCTL should be changed aside from when throttling because the ring for a context is full. In this situation, i915 will now wait while holding the object locks. This change was done because the code is much simpler to wait while holding the locks and we believe there isn't a huge benefit of dropping these locks. If this proves false we can restructure the code to drop the locks during the wait. IGT: https://patchwork.freedesktop.org/patch/447008/?series=93071&rev=1 media UMD: https://github.com/intel/media-driver/pull/1252 v2: (Matthew Brost) - Return proper error value if i915_request_create fails v3: (John Harrison) - Add comment explaining create / add order loops + locking - Update commit message explaining different in IOCTL behavior - Line wrap some comments - eb_add_request returns void - Return -EINVAL rather triggering BUG_ON if cmd parser used (Checkpatch) - Check eb->batch_len[*current_batch] v4: (CI) - Set batch len if passed if via execbuf args - Call __i915_request_skip after __i915_request_commit (Kernel test robot) - Initialize rq to NULL in eb_pin_timeline v5: (John Harrison) - Fix typo in comments near bb order loops Signed-off-by: Matthew Brost <matthew.brost@intel.com> Reviewed-by: John Harrison <John.C.Harrison@Intel.com> Signed-off-by: John Harrison <John.C.Harrison@Intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20211014172005.27155-21-matthew.brost@intel.com
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