[Mesa-dev] [PATCH 03/18] i965: Share the workaround bo between all contexts

[Chris Wilson]

Since the workaround bo is used strictly as a write-only buffer, we need
only allocate one per screen and use the same one from all contexts.

(The caveat here is during extension initialisation, where we write into
and read back register values from the buffer, but that is performed only
once for the first context - and baring synchronisation issues should not
be a problem. Safer would be to move that also to the screen.)

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 src/mesa/drivers/dri/i965/brw_pipe_control.c | 6 +++---
 src/mesa/drivers/dri/i965/intel_screen.c     | 4 ++++
 src/mesa/drivers/dri/i965/intel_screen.h     | 1 +
 3 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_pipe_control.c b/src/mesa/drivers/dri/i965/brw_pipe_control.c
index 7ee3cb6..05e14cd 100644
--- a/src/mesa/drivers/dri/i965/brw_pipe_control.c
+++ b/src/mesa/drivers/dri/i965/brw_pipe_control.c
@@ -341,12 +341,12 @@ brw_init_pipe_control(struct brw_context *brw,
     * the gen6 workaround because it involves actually writing to
     * the buffer, and the kernel doesn't let us write to the batch.
     */
-   brw->workaround_bo = drm_intel_bo_alloc(brw->bufmgr,
-                                           "pipe_control workaround",
-                                           4096, 4096);
+   brw->workaround_bo = brw->intelScreen->workaround_bo;
    if (brw->workaround_bo == NULL)
       return -ENOMEM;
 
+   drm_intel_bo_reference(brw->workaround_bo);
+
    brw->pipe_controls_since_last_cs_stall = 0;
 
    return 0;
diff --git a/src/mesa/drivers/dri/i965/intel_screen.c b/src/mesa/drivers/dri/i965/intel_screen.c
index 839a984..cd8e6eb 100644
--- a/src/mesa/drivers/dri/i965/intel_screen.c
+++ b/src/mesa/drivers/dri/i965/intel_screen.c
@@ -961,6 +961,7 @@ intelDestroyScreen(__DRIscreen * sPriv)
 {
    struct intel_screen *intelScreen = sPriv->driverPrivate;
 
+   drm_intel_bo_unreference(intelScreen->workaround_bo);
    dri_bufmgr_destroy(intelScreen->bufmgr);
    driDestroyOptionInfo(&intelScreen->optionCache);
 
@@ -1096,6 +1097,9 @@ intel_init_bufmgr(struct intel_screen *intelScreen)
       return false;
    }
 
+   intelScreen->workaround_bo =
+      drm_intel_bo_alloc(intelScreen->bufmgr, "pipe_control w/a", 4096, 4096);
+
    return true;
 }
 
diff --git a/src/mesa/drivers/dri/i965/intel_screen.h b/src/mesa/drivers/dri/i965/intel_screen.h
index 941e0fc..e55fddb 100644
--- a/src/mesa/drivers/dri/i965/intel_screen.h
+++ b/src/mesa/drivers/dri/i965/intel_screen.h
@@ -60,6 +60,7 @@ struct intel_screen
    bool has_context_reset_notification;
 
    dri_bufmgr *bufmgr;
+   drm_intel_bo *workaround_bo;
 
    /**
     * A unique ID for shader programs.
-- 
2.1.4