diff options
Diffstat (limited to 'src/gallium/drivers/nouveau/nouveau_buffer.c')
| -rw-r--r-- | src/gallium/drivers/nouveau/nouveau_buffer.c | 71 |
1 files changed, 69 insertions, 2 deletions
diff --git a/src/gallium/drivers/nouveau/nouveau_buffer.c b/src/gallium/drivers/nouveau/nouveau_buffer.c index 95905a8776f..0b21530e19b 100644 --- a/src/gallium/drivers/nouveau/nouveau_buffer.c +++ b/src/gallium/drivers/nouveau/nouveau_buffer.c @@ -129,6 +129,10 @@ nouveau_buffer_destroy(struct pipe_screen *pscreen, NOUVEAU_DRV_STAT(nouveau_screen(pscreen), buf_obj_current_count, -1); } +/* Set up a staging area for the transfer. This is either done in "regular" + * system memory if the driver supports push_data (nv50+) and the data is + * small enough (and permit_pb == true), or in GART memory. + */ static uint8_t * nouveau_transfer_staging(struct nouveau_context *nv, struct nouveau_transfer *tx, boolean permit_pb) @@ -155,7 +159,10 @@ nouveau_transfer_staging(struct nouveau_context *nv, return tx->map; } -/* Maybe just migrate to GART right away if we actually need to do this. */ +/* Copies data from the resource into the the transfer's temporary GART + * buffer. Also updates buf->data if present. + * + * Maybe just migrate to GART right away if we actually need to do this. */ static boolean nouveau_transfer_read(struct nouveau_context *nv, struct nouveau_transfer *tx) { @@ -210,7 +217,9 @@ nouveau_transfer_write(struct nouveau_context *nv, struct nouveau_transfer *tx, nouveau_fence_ref(nv->screen->fence.current, &buf->fence_wr); } - +/* Does a CPU wait for the buffer's backing data to become reliably accessible + * for write/read by waiting on the buffer's relevant fences. + */ static INLINE boolean nouveau_buffer_sync(struct nv04_resource *buf, unsigned rw) { @@ -283,6 +292,7 @@ nouveau_buffer_transfer_del(struct nouveau_context *nv, } } +/* Creates a cache in system memory of the buffer data. */ static boolean nouveau_buffer_cache(struct nouveau_context *nv, struct nv04_resource *buf) { @@ -317,6 +327,10 @@ nouveau_buffer_cache(struct nouveau_context *nv, struct nv04_resource *buf) #define NOUVEAU_TRANSFER_DISCARD \ (PIPE_TRANSFER_DISCARD_RANGE | PIPE_TRANSFER_DISCARD_WHOLE_RESOURCE) +/* Checks whether it is possible to completely discard the memory backing this + * resource. This can be useful if we would otherwise have to wait for a read + * operation to complete on this data. + */ static INLINE boolean nouveau_buffer_should_discard(struct nv04_resource *buf, unsigned usage) { @@ -327,6 +341,29 @@ nouveau_buffer_should_discard(struct nv04_resource *buf, unsigned usage) return buf->mm && nouveau_buffer_busy(buf, PIPE_TRANSFER_WRITE); } +/* Returns a pointer to a memory area representing a window into the + * resource's data. + * + * This may or may not be the _actual_ memory area of the resource. However + * when calling nouveau_buffer_transfer_unmap, if it wasn't the actual memory + * area, the contents of the returned map are copied over to the resource. + * + * The usage indicates what the caller plans to do with the map: + * + * WRITE means that the user plans to write to it + * + * READ means that the user plans on reading from it + * + * DISCARD_WHOLE_RESOURCE means that the whole resource is going to be + * potentially overwritten, and even if it isn't, the bits that aren't don't + * need to be maintained. + * + * DISCARD_RANGE means that all the data in the specified range is going to + * be overwritten. + * + * The strategy for determining what kind of memory area to return is complex, + * see comments inside of the function. + */ static void * nouveau_buffer_transfer_map(struct pipe_context *pipe, struct pipe_resource *resource, @@ -352,11 +389,17 @@ nouveau_buffer_transfer_map(struct pipe_context *pipe, if (buf->domain == NOUVEAU_BO_VRAM) { if (usage & NOUVEAU_TRANSFER_DISCARD) { + /* Set up a staging area for the user to write to. It will be copied + * back into VRAM on unmap. */ if (usage & PIPE_TRANSFER_DISCARD_WHOLE_RESOURCE) buf->status &= NOUVEAU_BUFFER_STATUS_REALLOC_MASK; nouveau_transfer_staging(nv, tx, TRUE); } else { if (buf->status & NOUVEAU_BUFFER_STATUS_GPU_WRITING) { + /* The GPU is currently writing to this buffer. Copy its current + * contents to a staging area in the GART. This is necessary since + * not the whole area being mapped is being discarded. + */ if (buf->data) { align_free(buf->data); buf->data = NULL; @@ -364,6 +407,8 @@ nouveau_buffer_transfer_map(struct pipe_context *pipe, nouveau_transfer_staging(nv, tx, FALSE); nouveau_transfer_read(nv, tx); } else { + /* The buffer is currently idle. Create a staging area for writes, + * and make sure that the cached data is up-to-date. */ if (usage & PIPE_TRANSFER_WRITE) nouveau_transfer_staging(nv, tx, TRUE); if (!buf->data) @@ -376,6 +421,8 @@ nouveau_buffer_transfer_map(struct pipe_context *pipe, return buf->data + box->x; } + /* At this point, buf->domain == GART */ + if (nouveau_buffer_should_discard(buf, usage)) { int ref = buf->base.reference.count - 1; nouveau_buffer_reallocate(nv->screen, buf, buf->domain); @@ -383,6 +430,12 @@ nouveau_buffer_transfer_map(struct pipe_context *pipe, nv->invalidate_resource_storage(nv, &buf->base, ref); } + /* Note that nouveau_bo_map ends up doing a nouveau_bo_wait with the + * relevant flags. If buf->mm is set, that means this resource is part of a + * larger slab bo that holds multiple resources. So in that case, don't + * wait on the whole slab and instead use the logic below to return a + * reasonable buffer for that case. + */ ret = nouveau_bo_map(buf->bo, buf->mm ? 0 : nouveau_screen_transfer_flags(usage), nv->client); @@ -396,6 +449,10 @@ nouveau_buffer_transfer_map(struct pipe_context *pipe, if ((usage & PIPE_TRANSFER_UNSYNCHRONIZED) || !buf->mm) return map; + /* If the GPU is currently reading/writing this buffer, we shouldn't + * interfere with its progress. So instead we either wait for the GPU to + * complete its operation, or set up a staging area to perform our work in. + */ if (nouveau_buffer_busy(buf, usage & PIPE_TRANSFER_READ_WRITE)) { if (unlikely(usage & PIPE_TRANSFER_DISCARD_WHOLE_RESOURCE)) { /* Discarding was not possible, must sync because @@ -403,6 +460,8 @@ nouveau_buffer_transfer_map(struct pipe_context *pipe, nouveau_buffer_sync(buf, usage & PIPE_TRANSFER_READ_WRITE); } else if (usage & PIPE_TRANSFER_DISCARD_RANGE) { + /* The whole range is being discarded, so it doesn't matter what was + * there before. No need to copy anything over. */ nouveau_transfer_staging(nv, tx, TRUE); map = tx->map; } else @@ -412,6 +471,8 @@ nouveau_buffer_transfer_map(struct pipe_context *pipe, else nouveau_buffer_sync(buf, usage & PIPE_TRANSFER_READ_WRITE); } else { + /* It is expected that the returned buffer be a representation of the + * data in question, so we must copy it over from the buffer. */ nouveau_transfer_staging(nv, tx, TRUE); if (tx->map) memcpy(tx->map, map, box->width); @@ -435,6 +496,12 @@ nouveau_buffer_transfer_flush_region(struct pipe_context *pipe, nouveau_transfer_write(nouveau_context(pipe), tx, box->x, box->width); } +/* Unmap stage of the transfer. If it was a WRITE transfer and the map that + * was returned was not the real resource's data, this needs to transfer the + * data back to the resource. + * + * Also marks vbo/cb dirty if the buffer's binding + */ static void nouveau_buffer_transfer_unmap(struct pipe_context *pipe, struct pipe_transfer *transfer) |