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Diffstat (limited to 'drivers/gpu/drm/i915/i915_deps.c')
-rw-r--r--drivers/gpu/drm/i915/i915_deps.c237
1 files changed, 237 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/i915_deps.c b/drivers/gpu/drm/i915/i915_deps.c
new file mode 100644
index 000000000..297b8e4e4
--- /dev/null
+++ b/drivers/gpu/drm/i915/i915_deps.c
@@ -0,0 +1,237 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2021 Intel Corporation
+ */
+
+#include <linux/dma-fence.h>
+#include <linux/slab.h>
+
+#include <drm/ttm/ttm_bo_api.h>
+
+#include "i915_deps.h"
+
+/**
+ * DOC: Set of utilities to dynamically collect dependencies into a
+ * structure which is fed into the GT migration code.
+ *
+ * Once we can do async unbinding, this is also needed to coalesce
+ * the migration fence with the unbind fences if these are coalesced
+ * post-migration.
+ *
+ * While collecting the individual dependencies, we store the refcounted
+ * struct dma_fence pointers in a realloc-managed pointer array, since
+ * that can be easily fed into a dma_fence_array. Other options are
+ * available, like for example an xarray for similarity with drm/sched.
+ * Can be changed easily if needed.
+ *
+ * A struct i915_deps need to be initialized using i915_deps_init().
+ * If i915_deps_add_dependency() or i915_deps_add_resv() return an
+ * error code they will internally call i915_deps_fini(), which frees
+ * all internal references and allocations.
+ */
+
+/* Min number of fence pointers in the array when an allocation occurs. */
+#define I915_DEPS_MIN_ALLOC_CHUNK 8U
+
+static void i915_deps_reset_fences(struct i915_deps *deps)
+{
+ if (deps->fences != &deps->single)
+ kfree(deps->fences);
+ deps->num_deps = 0;
+ deps->fences_size = 1;
+ deps->fences = &deps->single;
+}
+
+/**
+ * i915_deps_init - Initialize an i915_deps structure
+ * @deps: Pointer to the i915_deps structure to initialize.
+ * @gfp: The allocation mode for subsequenst allocations.
+ */
+void i915_deps_init(struct i915_deps *deps, gfp_t gfp)
+{
+ deps->fences = NULL;
+ deps->gfp = gfp;
+ i915_deps_reset_fences(deps);
+}
+
+/**
+ * i915_deps_fini - Finalize an i915_deps structure
+ * @deps: Pointer to the i915_deps structure to finalize.
+ *
+ * This function drops all fence references taken, conditionally frees and
+ * then resets the fences array.
+ */
+void i915_deps_fini(struct i915_deps *deps)
+{
+ unsigned int i;
+
+ for (i = 0; i < deps->num_deps; ++i)
+ dma_fence_put(deps->fences[i]);
+
+ if (deps->fences != &deps->single)
+ kfree(deps->fences);
+}
+
+static int i915_deps_grow(struct i915_deps *deps, struct dma_fence *fence,
+ const struct ttm_operation_ctx *ctx)
+{
+ int ret;
+
+ if (deps->num_deps >= deps->fences_size) {
+ unsigned int new_size = 2 * deps->fences_size;
+ struct dma_fence **new_fences;
+
+ new_size = max(new_size, I915_DEPS_MIN_ALLOC_CHUNK);
+ new_fences = kmalloc_array(new_size, sizeof(*new_fences), deps->gfp);
+ if (!new_fences)
+ goto sync;
+
+ memcpy(new_fences, deps->fences,
+ deps->fences_size * sizeof(*new_fences));
+ swap(new_fences, deps->fences);
+ if (new_fences != &deps->single)
+ kfree(new_fences);
+ deps->fences_size = new_size;
+ }
+ deps->fences[deps->num_deps++] = dma_fence_get(fence);
+ return 0;
+
+sync:
+ if (ctx->no_wait_gpu && !dma_fence_is_signaled(fence)) {
+ ret = -EBUSY;
+ goto unref;
+ }
+
+ ret = dma_fence_wait(fence, ctx->interruptible);
+ if (ret)
+ goto unref;
+
+ ret = fence->error;
+ if (ret)
+ goto unref;
+
+ return 0;
+
+unref:
+ i915_deps_fini(deps);
+ return ret;
+}
+
+/**
+ * i915_deps_sync - Wait for all the fences in the dependency collection
+ * @deps: Pointer to the i915_deps structure the fences of which to wait for.
+ * @ctx: Pointer to a struct ttm_operation_ctx indicating how the waits
+ * should be performed.
+ *
+ * This function waits for fences in the dependency collection. If it
+ * encounters an error during the wait or a fence error, the wait for
+ * further fences is aborted and the error returned.
+ *
+ * Return: Zero if successful, Negative error code on error.
+ */
+int i915_deps_sync(const struct i915_deps *deps, const struct ttm_operation_ctx *ctx)
+{
+ struct dma_fence **fences = deps->fences;
+ unsigned int i;
+ int ret = 0;
+
+ for (i = 0; i < deps->num_deps; ++i, ++fences) {
+ if (ctx->no_wait_gpu && !dma_fence_is_signaled(*fences)) {
+ ret = -EBUSY;
+ break;
+ }
+
+ ret = dma_fence_wait(*fences, ctx->interruptible);
+ if (!ret)
+ ret = (*fences)->error;
+ if (ret)
+ break;
+ }
+
+ return ret;
+}
+
+/**
+ * i915_deps_add_dependency - Add a fence to the dependency collection
+ * @deps: Pointer to the i915_deps structure a fence is to be added to.
+ * @fence: The fence to add.
+ * @ctx: Pointer to a struct ttm_operation_ctx indicating how waits are to
+ * be performed if waiting.
+ *
+ * Adds a fence to the dependency collection, and takes a reference on it.
+ * If the fence context is not zero and there was a later fence from the
+ * same fence context already added, then the fence is not added to the
+ * dependency collection. If the fence context is not zero and there was
+ * an earlier fence already added, then the fence will replace the older
+ * fence from the same context and the reference on the earlier fence will
+ * be dropped.
+ * If there is a failure to allocate memory to accommodate the new fence to
+ * be added, the new fence will instead be waited for and an error may
+ * be returned; depending on the value of @ctx, or if there was a fence
+ * error. If an error was returned, the dependency collection will be
+ * finalized and all fence reference dropped.
+ *
+ * Return: 0 if success. Negative error code on error.
+ */
+int i915_deps_add_dependency(struct i915_deps *deps,
+ struct dma_fence *fence,
+ const struct ttm_operation_ctx *ctx)
+{
+ unsigned int i;
+ int ret;
+
+ if (!fence)
+ return 0;
+
+ if (dma_fence_is_signaled(fence)) {
+ ret = fence->error;
+ if (ret)
+ i915_deps_fini(deps);
+ return ret;
+ }
+
+ for (i = 0; i < deps->num_deps; ++i) {
+ struct dma_fence *entry = deps->fences[i];
+
+ if (!entry->context || entry->context != fence->context)
+ continue;
+
+ if (dma_fence_is_later(fence, entry)) {
+ dma_fence_put(entry);
+ deps->fences[i] = dma_fence_get(fence);
+ }
+
+ return 0;
+ }
+
+ return i915_deps_grow(deps, fence, ctx);
+}
+
+/**
+ * i915_deps_add_resv - Add the fences of a reservation object to a dependency
+ * collection.
+ * @deps: Pointer to the i915_deps structure a fence is to be added to.
+ * @resv: The reservation object, then fences of which to add.
+ * @ctx: Pointer to a struct ttm_operation_ctx indicating how waits are to
+ * be performed if waiting.
+ *
+ * Calls i915_deps_add_depencency() on the indicated fences of @resv.
+ *
+ * Return: Zero on success. Negative error code on error.
+ */
+int i915_deps_add_resv(struct i915_deps *deps, struct dma_resv *resv,
+ const struct ttm_operation_ctx *ctx)
+{
+ struct dma_resv_iter iter;
+ struct dma_fence *fence;
+
+ dma_resv_assert_held(resv);
+ dma_resv_for_each_fence(&iter, resv, dma_resv_usage_rw(true), fence) {
+ int ret = i915_deps_add_dependency(deps, fence, ctx);
+
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}