[Mesa-dev] [PATCH 04/70] i965: Share the workaround bo between all contexts

[Chris Wilson]

On Mon, Aug 10, 2015 at 02:25:41PM +0300, Martin Peres wrote:
> On 07/08/15 23:13, Chris Wilson wrote:
> >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.)
> >
> >v2: Give the workaround bo its own init function and don't piggy back
> >intel_bufmgr_init() since it is not that related.
> >
> >Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> >Cc: Kenneth Graunke <kenneth at whitecape.org>
> >Cc: Martin Peres <martin.peres at linux.intel.com>
> >---
> >  src/mesa/drivers/dri/i965/brw_context.c      |  7 +------
> >  src/mesa/drivers/dri/i965/brw_context.h      |  4 ++--
> >  src/mesa/drivers/dri/i965/brw_pipe_control.c | 13 ++++---------
> >  src/mesa/drivers/dri/i965/intel_screen.c     | 15 +++++++++++++++
> >  src/mesa/drivers/dri/i965/intel_screen.h     |  1 +
> >  5 files changed, 23 insertions(+), 17 deletions(-)
> >
> >diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/dri/i965/brw_context.c
> >index efcd91a..ac744d7 100644
> >--- a/src/mesa/drivers/dri/i965/brw_context.c
> >+++ b/src/mesa/drivers/dri/i965/brw_context.c
> >@@ -819,12 +819,7 @@ brwCreateContext(gl_api api,
> >        }
> >     }
> >-   if (brw_init_pipe_control(brw, devinfo)) {
> >-      *dri_ctx_error = __DRI_CTX_ERROR_NO_MEMORY;
> >-      intelDestroyContext(driContextPriv);
> >-      return false;
> >-   }
> >-
> >+   brw_init_pipe_control(brw, devinfo);
> >     brw_init_state(brw);
> >     intelInitExtensions(ctx);
> >diff --git a/src/mesa/drivers/dri/i965/brw_context.h b/src/mesa/drivers/dri/i965/brw_context.h
> >index ffdf821..166b852 100644
> >--- a/src/mesa/drivers/dri/i965/brw_context.h
> >+++ b/src/mesa/drivers/dri/i965/brw_context.h
> >@@ -2016,8 +2016,8 @@ gen9_use_linear_1d_layout(const struct brw_context *brw,
> >                            const struct intel_mipmap_tree *mt);
> >  /* brw_pipe_control.c */
> >-int brw_init_pipe_control(struct brw_context *brw,
> >-			  const struct brw_device_info *info);
> >+void brw_init_pipe_control(struct brw_context *brw,
> >+                           const struct brw_device_info *info);
> >  void brw_fini_pipe_control(struct brw_context *brw);
> >  void brw_emit_pipe_control_flush(struct brw_context *brw, uint32_t flags);
> >diff --git a/src/mesa/drivers/dri/i965/brw_pipe_control.c b/src/mesa/drivers/dri/i965/brw_pipe_control.c
> >index 7ee3cb6..872bfe8 100644
> >--- a/src/mesa/drivers/dri/i965/brw_pipe_control.c
> >+++ b/src/mesa/drivers/dri/i965/brw_pipe_control.c
> >@@ -330,26 +330,21 @@ brw_emit_mi_flush(struct brw_context *brw)
> >     brw_render_cache_set_clear(brw);
> >  }
> >-int
> >+void
> >  brw_init_pipe_control(struct brw_context *brw,
> >                        const struct brw_device_info *devinfo)
> >  {
> >     if (devinfo->gen < 6)
> >-      return 0;
> >+      return;
> >     /* We can't just use brw_state_batch to get a chunk of space for
> >      * 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);
> >-   if (brw->workaround_bo == NULL)
> >-      return -ENOMEM;
> >+   brw->workaround_bo = brw->intelScreen->workaround_bo;
> >+   drm_intel_bo_reference(brw->workaround_bo);
> 
> Why do you need reference counting here? Why not simply destroy the
> buffer when the screen is destroyed? I would assume that a screen
> could not be destroyed until all its associated contexts are gone,
> right?

Because it makes me feel happier!

You are right, it can be removed and replaced with a comment.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre