[Mesa-dev] [PATCH] virgl: clear render state before submitting clear command

[Gert Wollny]

Virgl/virglrenderer implements the gallium clear command via a call to
glClear. However, gallium clear does not take render states like e.g.
RASTERIZER_DISCARD into account, but glClear does, and gallium st_Clear
does not updated the latest rendering state on the host. Hence, in order
to properly emulate gallium clear with glClear, all rendering states that
influence glClear must be set to their default values on the host before
submitting the actual clear command and restore the original state
afterwards (Thanks to Ilia Mirkin for helpint me understand this).

This patch implements the according mechanism in virgl_clear, the clear state
is defined like in mesa/st/st_cb_clear.c: st_init_clear.

Fixes CTS:
   dEQP-GLES3.functional.rasterizer_discard.fbo.*

Signed-off-by: Gert Wollny <gert.wollny at collabora.com>
---
PS : I have no mesa commits rights. 

 src/gallium/drivers/virgl/virgl_context.c | 24 ++++++++++++++++++-----
 src/gallium/drivers/virgl/virgl_context.h |  2 ++
 2 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/src/gallium/drivers/virgl/virgl_context.c b/src/gallium/drivers/virgl/virgl_context.c
index 8d701bb8f4..55ddbcf7df 100644
--- a/src/gallium/drivers/virgl/virgl_context.c
+++ b/src/gallium/drivers/virgl/virgl_context.c
@@ -305,9 +305,8 @@ static void virgl_bind_rasterizer_state(struct pipe_context *ctx,
                                                 void *rs_state)
 {
    struct virgl_context *vctx = virgl_context(ctx);
-   uint32_t handle = (unsigned long)rs_state;
-
-   virgl_encode_bind_object(vctx, handle, VIRGL_OBJECT_RASTERIZER);
+   vctx->last_render_state = rs_state;
+   virgl_encode_bind_object(vctx, (unsigned long)rs_state, VIRGL_OBJECT_RASTERIZER);
 }
 
 static void virgl_delete_rasterizer_state(struct pipe_context *ctx,
@@ -568,8 +567,19 @@ static void virgl_clear(struct pipe_context *ctx,
                                 double depth, unsigned stencil)
 {
    struct virgl_context *vctx = virgl_context(ctx);
+   struct pipe_rasterizer_state *old_state = vctx->last_render_state;
 
+   if (!vctx->clear_render_state) {
+      struct pipe_rasterizer_state clear_state;
+      memset(&clear_state, 0, sizeof(clear_state));
+      clear_state.depth_clip = 1;
+      clear_state.bottom_edge_rule = 1;
+      clear_state.half_pixel_center = 1;
+      vctx->clear_render_state = virgl_create_rasterizer_state(ctx, &clear_state);
+   }
+   virgl_bind_rasterizer_state(ctx, vctx->clear_render_state);
    virgl_encode_clear(vctx, buffers, color, depth, stencil);
+   virgl_bind_rasterizer_state(ctx, old_state);
 }
 
 static void virgl_draw_vbo(struct pipe_context *ctx,
@@ -844,6 +854,9 @@ virgl_context_destroy( struct pipe_context *ctx )
    struct virgl_context *vctx = virgl_context(ctx);
    struct virgl_screen *rs = virgl_screen(ctx->screen);
 
+   if (vctx->clear_render_state)
+      virgl_delete_rasterizer_state(ctx, vctx->clear_render_state);
+
    vctx->framebuffer.zsbuf = NULL;
    vctx->framebuffer.nr_cbufs = 0;
    virgl_encoder_destroy_sub_ctx(vctx, vctx->hw_sub_ctx_id);
@@ -948,6 +961,7 @@ struct pipe_context *virgl_context_create(struct pipe_screen *pscreen,
    virgl_encoder_create_sub_ctx(vctx, vctx->hw_sub_ctx_id);
 
    virgl_encoder_set_sub_ctx(vctx, vctx->hw_sub_ctx_id);
+
    return &vctx->base;
 fail:
    return NULL;
diff --git a/src/gallium/drivers/virgl/virgl_context.h b/src/gallium/drivers/virgl/virgl_context.h
index 3492dcfa49..a1c1d1a60c 100644
--- a/src/gallium/drivers/virgl/virgl_context.h
+++ b/src/gallium/drivers/virgl/virgl_context.h
@@ -74,6 +74,8 @@ struct virgl_context {
 
    struct primconvert_context *primconvert;
    uint32_t hw_sub_ctx_id;
+   void *last_render_state;
+   void *clear_render_state;
 };
 
 static inline struct virgl_sampler_view *
-- 
2.17.0