diff options
Diffstat (limited to 'drivers/dma-buf/dma-fence-unwrap.c')
| -rw-r--r-- | drivers/dma-buf/dma-fence-unwrap.c | 176 |
1 files changed, 176 insertions, 0 deletions
diff --git a/drivers/dma-buf/dma-fence-unwrap.c b/drivers/dma-buf/dma-fence-unwrap.c new file mode 100644 index 000000000..628af51c8 --- /dev/null +++ b/drivers/dma-buf/dma-fence-unwrap.c @@ -0,0 +1,176 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * dma-fence-util: misc functions for dma_fence objects + * + * Copyright (C) 2022 Advanced Micro Devices, Inc. + * Authors: + * Christian König <christian.koenig@amd.com> + */ + +#include <linux/dma-fence.h> +#include <linux/dma-fence-array.h> +#include <linux/dma-fence-chain.h> +#include <linux/dma-fence-unwrap.h> +#include <linux/slab.h> + +/* Internal helper to start new array iteration, don't use directly */ +static struct dma_fence * +__dma_fence_unwrap_array(struct dma_fence_unwrap *cursor) +{ + cursor->array = dma_fence_chain_contained(cursor->chain); + cursor->index = 0; + return dma_fence_array_first(cursor->array); +} + +/** + * dma_fence_unwrap_first - return the first fence from fence containers + * @head: the entrypoint into the containers + * @cursor: current position inside the containers + * + * Unwraps potential dma_fence_chain/dma_fence_array containers and return the + * first fence. + */ +struct dma_fence *dma_fence_unwrap_first(struct dma_fence *head, + struct dma_fence_unwrap *cursor) +{ + cursor->chain = dma_fence_get(head); + return __dma_fence_unwrap_array(cursor); +} +EXPORT_SYMBOL_GPL(dma_fence_unwrap_first); + +/** + * dma_fence_unwrap_next - return the next fence from a fence containers + * @cursor: current position inside the containers + * + * Continue unwrapping the dma_fence_chain/dma_fence_array containers and return + * the next fence from them. + */ +struct dma_fence *dma_fence_unwrap_next(struct dma_fence_unwrap *cursor) +{ + struct dma_fence *tmp; + + ++cursor->index; + tmp = dma_fence_array_next(cursor->array, cursor->index); + if (tmp) + return tmp; + + cursor->chain = dma_fence_chain_walk(cursor->chain); + return __dma_fence_unwrap_array(cursor); +} +EXPORT_SYMBOL_GPL(dma_fence_unwrap_next); + +/* Implementation for the dma_fence_merge() marco, don't use directly */ +struct dma_fence *__dma_fence_unwrap_merge(unsigned int num_fences, + struct dma_fence **fences, + struct dma_fence_unwrap *iter) +{ + struct dma_fence_array *result; + struct dma_fence *tmp, **array; + ktime_t timestamp; + unsigned int i; + size_t count; + + count = 0; + timestamp = ns_to_ktime(0); + for (i = 0; i < num_fences; ++i) { + dma_fence_unwrap_for_each(tmp, &iter[i], fences[i]) { + if (!dma_fence_is_signaled(tmp)) { + ++count; + } else { + ktime_t t = dma_fence_timestamp(tmp); + + if (ktime_after(t, timestamp)) + timestamp = t; + } + } + } + + /* + * If we couldn't find a pending fence just return a private signaled + * fence with the timestamp of the last signaled one. + */ + if (count == 0) + return dma_fence_allocate_private_stub(timestamp); + + array = kmalloc_array(count, sizeof(*array), GFP_KERNEL); + if (!array) + return NULL; + + /* + * This trashes the input fence array and uses it as position for the + * following merge loop. This works because the dma_fence_merge() + * wrapper macro is creating this temporary array on the stack together + * with the iterators. + */ + for (i = 0; i < num_fences; ++i) + fences[i] = dma_fence_unwrap_first(fences[i], &iter[i]); + + count = 0; + do { + unsigned int sel; + +restart: + tmp = NULL; + for (i = 0; i < num_fences; ++i) { + struct dma_fence *next; + + while (fences[i] && dma_fence_is_signaled(fences[i])) + fences[i] = dma_fence_unwrap_next(&iter[i]); + + next = fences[i]; + if (!next) + continue; + + /* + * We can't guarantee that inpute fences are ordered by + * context, but it is still quite likely when this + * function is used multiple times. So attempt to order + * the fences by context as we pass over them and merge + * fences with the same context. + */ + if (!tmp || tmp->context > next->context) { + tmp = next; + sel = i; + + } else if (tmp->context < next->context) { + continue; + + } else if (dma_fence_is_later(tmp, next)) { + fences[i] = dma_fence_unwrap_next(&iter[i]); + goto restart; + } else { + fences[sel] = dma_fence_unwrap_next(&iter[sel]); + goto restart; + } + } + + if (tmp) { + array[count++] = dma_fence_get(tmp); + fences[sel] = dma_fence_unwrap_next(&iter[sel]); + } + } while (tmp); + + if (count == 0) { + tmp = dma_fence_allocate_private_stub(ktime_get()); + goto return_tmp; + } + + if (count == 1) { + tmp = array[0]; + goto return_tmp; + } + + result = dma_fence_array_create(count, array, + dma_fence_context_alloc(1), + 1, false); + if (!result) { + tmp = NULL; + goto return_tmp; + } + return &result->base; + +return_tmp: + kfree(array); + return tmp; +} +EXPORT_SYMBOL_GPL(__dma_fence_unwrap_merge); |