util: remove LIST_IS_EMPTY macro

[mesa.git] / src / gallium / drivers / radeonsi / si_fence.c

/*
 * Copyright 2013-2017 Advanced Micro Devices, Inc.
 * All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 */

#include <libsync.h>

#include "util/os_time.h"
#include "util/u_memory.h"
#include "util/u_queue.h"
#include "util/u_upload_mgr.h"

#include "si_build_pm4.h"

struct si_fine_fence {
        struct si_resource *buf;
        unsigned offset;
};

struct si_multi_fence {
        struct pipe_reference reference;
        struct pipe_fence_handle *gfx;
        struct pipe_fence_handle *sdma;
        struct tc_unflushed_batch_token *tc_token;
        struct util_queue_fence ready;

        /* If the context wasn't flushed at fence creation, this is non-NULL. */
        struct {
                struct si_context *ctx;
                unsigned ib_index;
        } gfx_unflushed;

        struct si_fine_fence fine;
};

/**
 * Write an EOP event.
 *
 * \param event         EVENT_TYPE_*
 * \param event_flags   Optional cache flush flags (TC)
 * \param dst_sel       MEM or TC_L2
 * \param int_sel       NONE or SEND_DATA_AFTER_WR_CONFIRM
 * \param data_sel      DISCARD, VALUE_32BIT, TIMESTAMP, or GDS
 * \param buf           Buffer
 * \param va            GPU address
 * \param old_value     Previous fence value (for a bug workaround)
 * \param new_value     Fence value to write for this event.
 */
void si_cp_release_mem(struct si_context *ctx, struct radeon_cmdbuf *cs,
                       unsigned event, unsigned event_flags,
                       unsigned dst_sel, unsigned int_sel, unsigned data_sel,
                       struct si_resource *buf, uint64_t va,
                       uint32_t new_fence, unsigned query_type)
{
        unsigned op = EVENT_TYPE(event) |
                      EVENT_INDEX(event == V_028A90_CS_DONE ||
                                  event == V_028A90_PS_DONE ? 6 : 5) |
                      event_flags;
        unsigned sel = EOP_DST_SEL(dst_sel) |
                       EOP_INT_SEL(int_sel) |
                       EOP_DATA_SEL(data_sel);
        bool compute_ib = !ctx->has_graphics ||
                          cs == ctx->prim_discard_compute_cs;

        if (ctx->chip_class >= GFX9 ||
            (compute_ib && ctx->chip_class >= GFX7)) {
                /* A ZPASS_DONE or PIXEL_STAT_DUMP_EVENT (of the DB occlusion
                 * counters) must immediately precede every timestamp event to
                 * prevent a GPU hang on GFX9.
                 *
                 * Occlusion queries don't need to do it here, because they
                 * always do ZPASS_DONE before the timestamp.
                 */
                if (ctx->chip_class == GFX9 && !compute_ib &&
                    query_type != PIPE_QUERY_OCCLUSION_COUNTER &&
                    query_type != PIPE_QUERY_OCCLUSION_PREDICATE &&
                    query_type != PIPE_QUERY_OCCLUSION_PREDICATE_CONSERVATIVE) {
                        struct si_resource *scratch = ctx->eop_bug_scratch;

                        assert(16 * ctx->screen->info.num_render_backends <=
                               scratch->b.b.width0);
                        radeon_emit(cs, PKT3(PKT3_EVENT_WRITE, 2, 0));
                        radeon_emit(cs, EVENT_TYPE(EVENT_TYPE_ZPASS_DONE) | EVENT_INDEX(1));
                        radeon_emit(cs, scratch->gpu_address);
                        radeon_emit(cs, scratch->gpu_address >> 32);

                        radeon_add_to_buffer_list(ctx, ctx->gfx_cs, scratch,
                                                  RADEON_USAGE_WRITE, RADEON_PRIO_QUERY);
                }

                radeon_emit(cs, PKT3(PKT3_RELEASE_MEM, ctx->chip_class >= GFX9 ? 6 : 5, 0));
                radeon_emit(cs, op);
                radeon_emit(cs, sel);
                radeon_emit(cs, va);            /* address lo */
                radeon_emit(cs, va >> 32);      /* address hi */
                radeon_emit(cs, new_fence);     /* immediate data lo */
                radeon_emit(cs, 0); /* immediate data hi */
                if (ctx->chip_class >= GFX9)
                        radeon_emit(cs, 0); /* unused */
        } else {
                if (ctx->chip_class == GFX7 ||
                    ctx->chip_class == GFX8) {
                        struct si_resource *scratch = ctx->eop_bug_scratch;
                        uint64_t va = scratch->gpu_address;

                        /* Two EOP events are required to make all engines go idle
                         * (and optional cache flushes executed) before the timestamp
                         * is written.
                         */
                        radeon_emit(cs, PKT3(PKT3_EVENT_WRITE_EOP, 4, 0));
                        radeon_emit(cs, op);
                        radeon_emit(cs, va);
                        radeon_emit(cs, ((va >> 32) & 0xffff) | sel);
                        radeon_emit(cs, 0); /* immediate data */
                        radeon_emit(cs, 0); /* unused */

                        radeon_add_to_buffer_list(ctx, ctx->gfx_cs, scratch,
                                                  RADEON_USAGE_WRITE, RADEON_PRIO_QUERY);
                }

                radeon_emit(cs, PKT3(PKT3_EVENT_WRITE_EOP, 4, 0));
                radeon_emit(cs, op);
                radeon_emit(cs, va);
                radeon_emit(cs, ((va >> 32) & 0xffff) | sel);
                radeon_emit(cs, new_fence); /* immediate data */
                radeon_emit(cs, 0); /* unused */
        }

        if (buf) {
                radeon_add_to_buffer_list(ctx, ctx->gfx_cs, buf, RADEON_USAGE_WRITE,
                                          RADEON_PRIO_QUERY);
        }
}

unsigned si_cp_write_fence_dwords(struct si_screen *screen)
{
        unsigned dwords = 6;

        if (screen->info.chip_class == GFX7 ||
            screen->info.chip_class == GFX8)
                dwords *= 2;

        return dwords;
}

void si_cp_wait_mem(struct si_context *ctx, struct radeon_cmdbuf *cs,
                    uint64_t va, uint32_t ref, uint32_t mask, unsigned flags)
{
        radeon_emit(cs, PKT3(PKT3_WAIT_REG_MEM, 5, 0));
        radeon_emit(cs, WAIT_REG_MEM_MEM_SPACE(1) | flags);
        radeon_emit(cs, va);
        radeon_emit(cs, va >> 32);
        radeon_emit(cs, ref); /* reference value */
        radeon_emit(cs, mask); /* mask */
        radeon_emit(cs, 4); /* poll interval */
}

static void si_add_fence_dependency(struct si_context *sctx,
                                    struct pipe_fence_handle *fence)
{
        struct radeon_winsys *ws = sctx->ws;

        if (sctx->dma_cs)
                ws->cs_add_fence_dependency(sctx->dma_cs, fence, 0);
        ws->cs_add_fence_dependency(sctx->gfx_cs, fence, 0);
}

static void si_add_syncobj_signal(struct si_context *sctx,
                                  struct pipe_fence_handle *fence)
{
        sctx->ws->cs_add_syncobj_signal(sctx->gfx_cs, fence);
}

static void si_fence_reference(struct pipe_screen *screen,
                               struct pipe_fence_handle **dst,
                               struct pipe_fence_handle *src)
{
        struct radeon_winsys *ws = ((struct si_screen*)screen)->ws;
        struct si_multi_fence **sdst = (struct si_multi_fence **)dst;
        struct si_multi_fence *ssrc = (struct si_multi_fence *)src;

        if (pipe_reference(&(*sdst)->reference, &ssrc->reference)) {
                ws->fence_reference(&(*sdst)->gfx, NULL);
                ws->fence_reference(&(*sdst)->sdma, NULL);
                tc_unflushed_batch_token_reference(&(*sdst)->tc_token, NULL);
                si_resource_reference(&(*sdst)->fine.buf, NULL);
                FREE(*sdst);
        }
        *sdst = ssrc;
}

static struct si_multi_fence *si_create_multi_fence()
{
        struct si_multi_fence *fence = CALLOC_STRUCT(si_multi_fence);
        if (!fence)
                return NULL;

        pipe_reference_init(&fence->reference, 1);
        util_queue_fence_init(&fence->ready);

        return fence;
}

struct pipe_fence_handle *si_create_fence(struct pipe_context *ctx,
                                          struct tc_unflushed_batch_token *tc_token)
{
        struct si_multi_fence *fence = si_create_multi_fence();
        if (!fence)
                return NULL;

        util_queue_fence_reset(&fence->ready);
        tc_unflushed_batch_token_reference(&fence->tc_token, tc_token);

        return (struct pipe_fence_handle *)fence;
}

static bool si_fine_fence_signaled(struct radeon_winsys *rws,
                                   const struct si_fine_fence *fine)
{
        char *map = rws->buffer_map(fine->buf->buf, NULL, PIPE_TRANSFER_READ |
                                                          PIPE_TRANSFER_UNSYNCHRONIZED);
        if (!map)
                return false;

        uint32_t *fence = (uint32_t*)(map + fine->offset);
        return *fence != 0;
}

static void si_fine_fence_set(struct si_context *ctx,
                              struct si_fine_fence *fine,
                              unsigned flags)
{
        uint32_t *fence_ptr;

        assert(util_bitcount(flags & (PIPE_FLUSH_TOP_OF_PIPE | PIPE_FLUSH_BOTTOM_OF_PIPE)) == 1);

        /* Use cached system memory for the fence. */
        u_upload_alloc(ctx->cached_gtt_allocator, 0, 4, 4,
                       &fine->offset, (struct pipe_resource **)&fine->buf, (void **)&fence_ptr);
        if (!fine->buf)
                return;

        *fence_ptr = 0;

        if (flags & PIPE_FLUSH_TOP_OF_PIPE) {
                uint32_t value = 0x80000000;

                si_cp_write_data(ctx, fine->buf, fine->offset, 4,
                                 V_370_MEM, V_370_PFP, &value);
        } else if (flags & PIPE_FLUSH_BOTTOM_OF_PIPE) {
                uint64_t fence_va = fine->buf->gpu_address + fine->offset;

                radeon_add_to_buffer_list(ctx, ctx->gfx_cs, fine->buf,
                                          RADEON_USAGE_WRITE, RADEON_PRIO_QUERY);
                si_cp_release_mem(ctx, ctx->gfx_cs,
                                  V_028A90_BOTTOM_OF_PIPE_TS, 0,
                                  EOP_DST_SEL_MEM, EOP_INT_SEL_NONE,
                                  EOP_DATA_SEL_VALUE_32BIT,
                                  NULL, fence_va, 0x80000000,
                                  PIPE_QUERY_GPU_FINISHED);
        } else {
                assert(false);
        }
}

static bool si_fence_finish(struct pipe_screen *screen,
                            struct pipe_context *ctx,
                            struct pipe_fence_handle *fence,
                            uint64_t timeout)
{
        struct radeon_winsys *rws = ((struct si_screen*)screen)->ws;
        struct si_multi_fence *sfence = (struct si_multi_fence *)fence;
        struct si_context *sctx;
        int64_t abs_timeout = os_time_get_absolute_timeout(timeout);

        ctx = threaded_context_unwrap_sync(ctx);
        sctx = (struct si_context*)(ctx ? ctx : NULL);

        if (!util_queue_fence_is_signalled(&sfence->ready)) {
                if (sfence->tc_token) {
                        /* Ensure that si_flush_from_st will be called for
                         * this fence, but only if we're in the API thread
                         * where the context is current.
                         *
                         * Note that the batch containing the flush may already
                         * be in flight in the driver thread, so the fence
                         * may not be ready yet when this call returns.
                         */
                        threaded_context_flush(ctx, sfence->tc_token,
                                               timeout == 0);
                }

                if (!timeout)
                        return false;

                if (timeout == PIPE_TIMEOUT_INFINITE) {
                        util_queue_fence_wait(&sfence->ready);
                } else {
                        if (!util_queue_fence_wait_timeout(&sfence->ready, abs_timeout))
                                return false;
                }

                if (timeout && timeout != PIPE_TIMEOUT_INFINITE) {
                        int64_t time = os_time_get_nano();
                        timeout = abs_timeout > time ? abs_timeout - time : 0;
                }
        }

        if (sfence->sdma) {
                if (!rws->fence_wait(rws, sfence->sdma, timeout))
                        return false;

                /* Recompute the timeout after waiting. */
                if (timeout && timeout != PIPE_TIMEOUT_INFINITE) {
                        int64_t time = os_time_get_nano();
                        timeout = abs_timeout > time ? abs_timeout - time : 0;
                }
        }

        if (!sfence->gfx)
                return true;

        if (sfence->fine.buf &&
            si_fine_fence_signaled(rws, &sfence->fine)) {
                rws->fence_reference(&sfence->gfx, NULL);
                si_resource_reference(&sfence->fine.buf, NULL);
                return true;
        }

        /* Flush the gfx IB if it hasn't been flushed yet. */
        if (sctx && sfence->gfx_unflushed.ctx == sctx &&
            sfence->gfx_unflushed.ib_index == sctx->num_gfx_cs_flushes) {
                /* Section 4.1.2 (Signaling) of the OpenGL 4.6 (Core profile)
                 * spec says:
                 *
                 *    "If the sync object being blocked upon will not be
                 *     signaled in finite time (for example, by an associated
                 *     fence command issued previously, but not yet flushed to
                 *     the graphics pipeline), then ClientWaitSync may hang
                 *     forever. To help prevent this behavior, if
                 *     ClientWaitSync is called and all of the following are
                 *     true:
                 *
                 *     * the SYNC_FLUSH_COMMANDS_BIT bit is set in flags,
                 *     * sync is unsignaled when ClientWaitSync is called,
                 *     * and the calls to ClientWaitSync and FenceSync were
                 *       issued from the same context,
                 *
                 *     then the GL will behave as if the equivalent of Flush
                 *     were inserted immediately after the creation of sync."
                 *
                 * This means we need to flush for such fences even when we're
                 * not going to wait.
                 */
                si_flush_gfx_cs(sctx,
                                (timeout ? 0 : PIPE_FLUSH_ASYNC) |
                                 RADEON_FLUSH_START_NEXT_GFX_IB_NOW,
                                NULL);
                sfence->gfx_unflushed.ctx = NULL;

                if (!timeout)
                        return false;

                /* Recompute the timeout after all that. */
                if (timeout && timeout != PIPE_TIMEOUT_INFINITE) {
                        int64_t time = os_time_get_nano();
                        timeout = abs_timeout > time ? abs_timeout - time : 0;
                }
        }

        if (rws->fence_wait(rws, sfence->gfx, timeout))
                return true;

        /* Re-check in case the GPU is slow or hangs, but the commands before
         * the fine-grained fence have completed. */
        if (sfence->fine.buf &&
            si_fine_fence_signaled(rws, &sfence->fine))
                return true;

        return false;
}

static void si_create_fence_fd(struct pipe_context *ctx,
                               struct pipe_fence_handle **pfence, int fd,
                               enum pipe_fd_type type)
{
        struct si_screen *sscreen = (struct si_screen*)ctx->screen;
        struct radeon_winsys *ws = sscreen->ws;
        struct si_multi_fence *sfence;

        *pfence = NULL;

        sfence = si_create_multi_fence();
        if (!sfence)
                return;

        switch (type) {
        case PIPE_FD_TYPE_NATIVE_SYNC:
                if (!sscreen->info.has_fence_to_handle)
                        goto finish;

                sfence->gfx = ws->fence_import_sync_file(ws, fd);
                break;

        case PIPE_FD_TYPE_SYNCOBJ:
                if (!sscreen->info.has_syncobj)
                        goto finish;

                sfence->gfx = ws->fence_import_syncobj(ws, fd);
                break;

        default:
                unreachable("bad fence fd type when importing");
        }

finish:
        if (!sfence->gfx) {
                FREE(sfence);
                return;
        }

        *pfence = (struct pipe_fence_handle*)sfence;
}

static int si_fence_get_fd(struct pipe_screen *screen,
                           struct pipe_fence_handle *fence)
{
        struct si_screen *sscreen = (struct si_screen*)screen;
        struct radeon_winsys *ws = sscreen->ws;
        struct si_multi_fence *sfence = (struct si_multi_fence *)fence;
        int gfx_fd = -1, sdma_fd = -1;

        if (!sscreen->info.has_fence_to_handle)
                return -1;

        util_queue_fence_wait(&sfence->ready);

        /* Deferred fences aren't supported. */
        assert(!sfence->gfx_unflushed.ctx);
        if (sfence->gfx_unflushed.ctx)
                return -1;

        if (sfence->sdma) {
                sdma_fd = ws->fence_export_sync_file(ws, sfence->sdma);
                if (sdma_fd == -1)
                        return -1;
        }
        if (sfence->gfx) {
                gfx_fd = ws->fence_export_sync_file(ws, sfence->gfx);
                if (gfx_fd == -1) {
                        if (sdma_fd != -1)
                                close(sdma_fd);
                        return -1;
                }
        }

        /* If we don't have FDs at this point, it means we don't have fences
         * either. */
        if (sdma_fd == -1 && gfx_fd == -1)
                return ws->export_signalled_sync_file(ws);
        if (sdma_fd == -1)
                return gfx_fd;
        if (gfx_fd == -1)
                return sdma_fd;

        /* Get a fence that will be a combination of both fences. */
        sync_accumulate("radeonsi", &gfx_fd, sdma_fd);
        close(sdma_fd);
        return gfx_fd;
}

static void si_flush_from_st(struct pipe_context *ctx,
                             struct pipe_fence_handle **fence,
                             unsigned flags)
{
        struct pipe_screen *screen = ctx->screen;
        struct si_context *sctx = (struct si_context *)ctx;
        struct radeon_winsys *ws = sctx->ws;
        struct pipe_fence_handle *gfx_fence = NULL;
        struct pipe_fence_handle *sdma_fence = NULL;
        bool deferred_fence = false;
        struct si_fine_fence fine = {};
        unsigned rflags = PIPE_FLUSH_ASYNC;

        if (flags & PIPE_FLUSH_END_OF_FRAME)
                rflags |= PIPE_FLUSH_END_OF_FRAME;

        if (flags & (PIPE_FLUSH_TOP_OF_PIPE | PIPE_FLUSH_BOTTOM_OF_PIPE)) {
                assert(flags & PIPE_FLUSH_DEFERRED);
                assert(fence);

                si_fine_fence_set(sctx, &fine, flags);
        }

        /* DMA IBs are preambles to gfx IBs, therefore must be flushed first. */
        if (sctx->dma_cs)
                si_flush_dma_cs(sctx, rflags, fence ? &sdma_fence : NULL);

        if (!radeon_emitted(sctx->gfx_cs, sctx->initial_gfx_cs_size)) {
                if (fence)
                        ws->fence_reference(&gfx_fence, sctx->last_gfx_fence);
                if (!(flags & PIPE_FLUSH_DEFERRED))
                        ws->cs_sync_flush(sctx->gfx_cs);
        } else {
                /* Instead of flushing, create a deferred fence. Constraints:
                 * - The state tracker must allow a deferred flush.
                 * - The state tracker must request a fence.
                 * - fence_get_fd is not allowed.
                 * Thread safety in fence_finish must be ensured by the state tracker.
                 */
                if (flags & PIPE_FLUSH_DEFERRED &&
                    !(flags & PIPE_FLUSH_FENCE_FD) &&
                    fence) {
                        gfx_fence = sctx->ws->cs_get_next_fence(sctx->gfx_cs);
                        deferred_fence = true;
                } else {
                        si_flush_gfx_cs(sctx, rflags, fence ? &gfx_fence : NULL);
                }
        }

        /* Both engines can signal out of order, so we need to keep both fences. */
        if (fence) {
                struct si_multi_fence *multi_fence;

                if (flags & TC_FLUSH_ASYNC) {
                        multi_fence = (struct si_multi_fence *)*fence;
                        assert(multi_fence);
                } else {
                        multi_fence = si_create_multi_fence();
                        if (!multi_fence) {
                                ws->fence_reference(&sdma_fence, NULL);
                                ws->fence_reference(&gfx_fence, NULL);
                                goto finish;
                        }

                        screen->fence_reference(screen, fence, NULL);
                        *fence = (struct pipe_fence_handle*)multi_fence;
                }

                /* If both fences are NULL, fence_finish will always return true. */
                multi_fence->gfx = gfx_fence;
                multi_fence->sdma = sdma_fence;

                if (deferred_fence) {
                        multi_fence->gfx_unflushed.ctx = sctx;
                        multi_fence->gfx_unflushed.ib_index = sctx->num_gfx_cs_flushes;
                }

                multi_fence->fine = fine;
                fine.buf = NULL;

                if (flags & TC_FLUSH_ASYNC) {
                        util_queue_fence_signal(&multi_fence->ready);
                        tc_unflushed_batch_token_reference(&multi_fence->tc_token, NULL);
                }
        }
        assert(!fine.buf);
finish:
        if (!(flags & (PIPE_FLUSH_DEFERRED | PIPE_FLUSH_ASYNC))) {
                if (sctx->dma_cs)
                        ws->cs_sync_flush(sctx->dma_cs);
                ws->cs_sync_flush(sctx->gfx_cs);
        }
}

static void si_fence_server_signal(struct pipe_context *ctx,
                                   struct pipe_fence_handle *fence)
{
        struct si_context *sctx = (struct si_context *)ctx;
        struct si_multi_fence *sfence = (struct si_multi_fence *)fence;

        /* We should have at least one syncobj to signal */
        assert(sfence->sdma || sfence->gfx);

        if (sfence->sdma)
                si_add_syncobj_signal(sctx, sfence->sdma);
        if (sfence->gfx)
                si_add_syncobj_signal(sctx, sfence->gfx);

        /**
         * The spec does not require a flush here. We insert a flush
         * because syncobj based signals are not directly placed into
         * the command stream. Instead the signal happens when the
         * submission associated with the syncobj finishes execution.
         *
         * Therefore, we must make sure that we flush the pipe to avoid
         * new work being emitted and getting executed before the signal
         * operation.
         */
        si_flush_from_st(ctx, NULL, PIPE_FLUSH_ASYNC);
}

static void si_fence_server_sync(struct pipe_context *ctx,
                                 struct pipe_fence_handle *fence)
{
        struct si_context *sctx = (struct si_context *)ctx;
        struct si_multi_fence *sfence = (struct si_multi_fence *)fence;

        util_queue_fence_wait(&sfence->ready);

        /* Unflushed fences from the same context are no-ops. */
        if (sfence->gfx_unflushed.ctx &&
            sfence->gfx_unflushed.ctx == sctx)
                return;

        /* All unflushed commands will not start execution before
         * this fence dependency is signalled.
         *
         * Therefore we must flush before inserting the dependency
         */
        si_flush_from_st(ctx, NULL, PIPE_FLUSH_ASYNC);

        if (sfence->sdma)
                si_add_fence_dependency(sctx, sfence->sdma);
        if (sfence->gfx)
                si_add_fence_dependency(sctx, sfence->gfx);
}

void si_init_fence_functions(struct si_context *ctx)
{
        ctx->b.flush = si_flush_from_st;
        ctx->b.create_fence_fd = si_create_fence_fd;
        ctx->b.fence_server_sync = si_fence_server_sync;
        ctx->b.fence_server_signal = si_fence_server_signal;
}

void si_init_screen_fence_functions(struct si_screen *screen)
{
        screen->b.fence_finish = si_fence_finish;
        screen->b.fence_reference = si_fence_reference;
        screen->b.fence_get_fd = si_fence_get_fd;
}