i915: Disable the depth test whenever we don't have a depth buffer.

We were disabling it once at the moment we changed draw buffers, but
later enabling of depth test could turn it back on.  Fixes
fbo-nodepth-test.

Note that ctx->DrawBuffer has to be checked because during context
create we get called while it's still unset.  However, we know we'll
get an intel_draw_buffer() after that, so it's safe to make a silly
choice at this point.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=30080

2 files changed, 8 insertions, 2 deletions

diff --git a/src/mesa/drivers/dri/i915/i915_state.c b/src/mesa/drivers/dri/i915/i915_state.c
index 99212ad4fd1..73dda65261e 100644
--- a/src/mesa/drivers/dri/i915/i915_state.c
+++ b/src/mesa/drivers/dri/i915/i915_state.c
@@ -375,6 +375,9 @@ i915DepthMask(struct gl_context * ctx, GLboolean flag)
 
    DBG("%s flag (%d)\n", __FUNCTION__, flag);
 
+   if (!ctx->DrawBuffer || !ctx->DrawBuffer->Visual.depthBits)
+      flag = false;
+
    dw = i915->state.Ctx[I915_CTXREG_LIS6];
    if (flag && ctx->Depth.Test)
       dw |= S6_DEPTH_WRITE_ENABLE;
@@ -797,6 +800,10 @@ i915Enable(struct gl_context * ctx, GLenum cap, GLboolean state)
 
    case GL_DEPTH_TEST:
       dw = i915->state.Ctx[I915_CTXREG_LIS6];
+
+      if (!ctx->DrawBuffer || !ctx->DrawBuffer->Visual.depthBits)
+	 state = false;
+
       if (state)
          dw |= S6_DEPTH_TEST_ENABLE;
       else
diff --git a/src/mesa/drivers/dri/i915/i915_vtbl.c b/src/mesa/drivers/dri/i915/i915_vtbl.c
index 49ffd787695..95c56bc8893 100644
--- a/src/mesa/drivers/dri/i915/i915_vtbl.c
+++ b/src/mesa/drivers/dri/i915/i915_vtbl.c
@@ -798,8 +798,7 @@ i915_update_draw_buffer(struct intel_context *intel)
    /*
     * Update depth and stencil test state
     */
-   ctx->Driver.Enable(ctx, GL_DEPTH_TEST,
-		      (ctx->Depth.Test && fb->Visual.depthBits > 0));
+   ctx->Driver.Enable(ctx, GL_DEPTH_TEST, ctx->Depth.Test);
    ctx->Driver.Enable(ctx, GL_STENCIL_TEST,
 		      (ctx->Stencil.Enabled && fb->Visual.stencilBits > 0));