[Mesa-dev] [PATCH] r600g: fix lockups with dual_src_blend mode

[Marek Olšák]

I am not so familiar with this piece of code, but the idea sounds good.

In the future, we should just disable the dual src blending instead.
Shader recompilations certainly take more time than changing a couple
of blending registers.

Marek

On Mon, Aug 20, 2012 at 10:35 PM, Vadim Girlin <vadimgirlin at gmail.com> wrote:
> Add fake pixel exports if we have less than two when dual_src_blend is enabled.
>
> Fixes lockups with ext_framebuffer_multisample-
> alpha-to-coverage-dual-src-blend piglit test on juniper.
>
> Signed-off-by: Vadim Girlin <vadimgirlin at gmail.com>
> ---
>
> Tested on evergreen only.
>
> Don't know if it's documented somewhere, possibly we only need to adjust some
> config regs without adding fake export to the shader code.
>
>  src/gallium/drivers/r600/r600_shader.c | 37 +++++++++++++++++-----------------
>  1 file changed, 19 insertions(+), 18 deletions(-)
>
> diff --git a/src/gallium/drivers/r600/r600_shader.c b/src/gallium/drivers/r600/r600_shader.c
> index 834c0b3..aa65e4e 100644
> --- a/src/gallium/drivers/r600/r600_shader.c
> +++ b/src/gallium/drivers/r600/r600_shader.c
> @@ -1198,7 +1198,6 @@ static int r600_shader_from_tgsi(struct r600_context * rctx, struct r600_pipe_sh
>         ctx.colors_used = 0;
>         ctx.clip_vertex_write = 0;
>
> -       shader->nr_ps_color_exports = 0;
>         shader->nr_ps_max_color_exports = 0;
>
>         shader->two_side = (ctx.type == TGSI_PROCESSOR_FRAGMENT) && rctx->two_side;
> @@ -1587,7 +1586,6 @@ static int r600_shader_from_tgsi(struct r600_context * rctx, struct r600_pipe_sh
>                                 output[j].swizzle_w = rctx->alpha_to_one && rctx->multisample_enable && !rctx->cb0_is_integer ? 5 : 3;
>                                 output[j].array_base = next_pixel_base++;
>                                 output[j].type = V_SQ_CF_ALLOC_EXPORT_WORD0_SQ_EXPORT_PIXEL;
> -                               shader->nr_ps_color_exports++;
>                                 if (shader->fs_write_all && (rctx->chip_class >= EVERGREEN)) {
>                                         for (k = 1; k < rctx->nr_cbufs; k++) {
>                                                 j++;
> @@ -1603,7 +1601,6 @@ static int r600_shader_from_tgsi(struct r600_context * rctx, struct r600_pipe_sh
>                                                 output[j].array_base = next_pixel_base++;
>                                                 output[j].inst = BC_INST(ctx.bc, V_SQ_CF_ALLOC_EXPORT_WORD1_SQ_CF_INST_EXPORT);
>                                                 output[j].type = V_SQ_CF_ALLOC_EXPORT_WORD0_SQ_EXPORT_PIXEL;
> -                                               shader->nr_ps_color_exports++;
>                                         }
>                                 }
>                         } else if (shader->output[i].name == TGSI_SEMANTIC_POSITION) {
> @@ -1653,23 +1650,27 @@ static int r600_shader_from_tgsi(struct r600_context * rctx, struct r600_pipe_sh
>                         j++;
>         }
>
> -       /* add fake pixel export */
> -       if (ctx.type == TGSI_PROCESSOR_FRAGMENT && next_pixel_base == 0) {
> -               memset(&output[j], 0, sizeof(struct r600_bytecode_output));
> -               output[j].gpr = 0;
> -               output[j].elem_size = 3;
> -               output[j].swizzle_x = 7;
> -               output[j].swizzle_y = 7;
> -               output[j].swizzle_z = 7;
> -               output[j].swizzle_w = 7;
> -               output[j].burst_count = 1;
> -               output[j].barrier = 1;
> -               output[j].type = V_SQ_CF_ALLOC_EXPORT_WORD0_SQ_EXPORT_PIXEL;
> -               output[j].array_base = 0;
> -               output[j].inst = BC_INST(ctx.bc, V_SQ_CF_ALLOC_EXPORT_WORD1_SQ_CF_INST_EXPORT);
> -               j++;
> +       /* add fake pixel exports if we have less than
> +        * (1 + rctx->dual_src_blend) pixel exports */
> +       if (ctx.type == TGSI_PROCESSOR_FRAGMENT) {
> +               while (next_pixel_base <= rctx->dual_src_blend) {
> +                       memset(&output[j], 0, sizeof(struct r600_bytecode_output));
> +                       output[j].gpr = 0;
> +                       output[j].elem_size = 3;
> +                       output[j].swizzle_x = 7;
> +                       output[j].swizzle_y = 7;
> +                       output[j].swizzle_z = 7;
> +                       output[j].swizzle_w = 7;
> +                       output[j].burst_count = 1;
> +                       output[j].barrier = 1;
> +                       output[j].type = V_SQ_CF_ALLOC_EXPORT_WORD0_SQ_EXPORT_PIXEL;
> +                       output[j].array_base = next_pixel_base++;
> +                       output[j].inst = BC_INST(ctx.bc, V_SQ_CF_ALLOC_EXPORT_WORD1_SQ_CF_INST_EXPORT);
> +                       j++;
> +               }
>         }
>
> +       shader->nr_ps_color_exports = next_pixel_base;
>         noutput = j;
>
>         /* set export done on last export of each type */
> --
> 1.7.11.4
>
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