gpu: nvgpu: Dynamic betacb size

Allow querying and setting default betacb size via debugfs. For global buffers
the value takes effect upon first boot of GPU, and has no effect after that.

Bug 1628352

Change-Id: Ib63f4299249c41eab1b36cc501b525cc54211195
Signed-off-by: Terje Bergstrom <tbergstrom@nvidia.com>
Reviewed-on: http://git-master/r/733328

1 files changed, 3 insertions, 2 deletions

diff --git a/drivers/gpu/nvgpu/gm20b/gr_gm20b.c b/drivers/gpu/nvgpu/gm20b/gr_gm20b.c
index 74761258..55a21c98 100644
--- a/drivers/gpu/nvgpu/gm20b/gr_gm20b.c
+++ b/drivers/gpu/nvgpu/gm20b/gr_gm20b.c
@@ -85,8 +85,9 @@ static void gr_gm20b_cb_size_default(struct gk20a *g)
 {
         struct gr_gk20a *gr = &g->gr;
 
-        gr->attrib_cb_default_size =
-                gr_gpc0_ppc0_cbm_beta_cb_size_v_default_v();
+        if (!gr->attrib_cb_default_size)
+                gr->attrib_cb_default_size =
+                        gr_gpc0_ppc0_cbm_beta_cb_size_v_default_v();
         gr->alpha_cb_default_size =
                 gr_gpc0_ppc0_cbm_alpha_cb_size_v_default_v();
 }