[Mesa-dev] [PATCH] i965/skl: Emit new 3DSTATE_VF_COMPONENT_PACKING

[Ben Widawsky]

Update:

I no longer thing we should merge this patch. A note in the programming has been
introduced stating that we should not program this state packet without enabling
at least one component.

On Wed, Jul 01, 2015 at 04:06:54PM -0700, Ben Widawsky wrote:
> We don't yet have a use for this state, but initializing it to known values is
> always considered wise. In general NULL state can probably go in the misc state
> upload, I only put it here because I assume it might be useful at some point.
> 
> Signed-off-by: Ben Widawsky <ben at bwidawsk.net>
> ---
> 
> I've had this patch sitting around for almost 3 months now. I believe we like to
> initialize new fields as a general rule of thumb.
> 
> ---
>  src/mesa/drivers/dri/i965/brw_defines.h      |  2 ++
>  src/mesa/drivers/dri/i965/gen8_draw_upload.c | 29 ++++++++++++++++++++++++++++
>  2 files changed, 31 insertions(+)
> 
> diff --git a/src/mesa/drivers/dri/i965/brw_defines.h b/src/mesa/drivers/dri/i965/brw_defines.h
> index 66b9abc..444d974 100644
> --- a/src/mesa/drivers/dri/i965/brw_defines.h
> +++ b/src/mesa/drivers/dri/i965/brw_defines.h
> @@ -1713,6 +1713,8 @@ enum brw_message_target {
>  
>  #define _3DSTATE_VF_TOPOLOGY                    0x784b /* GEN8+ */
>  
> +#define _3DSTATE_VF_COMPONENT_PACKING           0x7855 /* GEN9+ */
> +
>  #define _3DSTATE_WM_CHROMAKEY			0x784c /* GEN8+ */
>  
>  #define _3DSTATE_URB_VS                         0x7830 /* GEN7+ */
> diff --git a/src/mesa/drivers/dri/i965/gen8_draw_upload.c b/src/mesa/drivers/dri/i965/gen8_draw_upload.c
> index 1af90ec..f6e7fc8 100644
> --- a/src/mesa/drivers/dri/i965/gen8_draw_upload.c
> +++ b/src/mesa/drivers/dri/i965/gen8_draw_upload.c
> @@ -35,6 +35,33 @@
>  #include "intel_batchbuffer.h"
>  #include "intel_buffer_objects.h"
>  
> +/**
> + * Emits a null component packing state.
> + *
> + * Paraphrasing the docs: "This command is used to specify which 32-bit
> + * components are "enabled" to be stored in the URB, and which are "disabled".
> + * Disabling all four components for a given Vertex Element will result in no
> + * data stored for that element. Note that any insertion of SGVs
> + * (3DSTATE_VF_SGVS) is performed before the packing operation."
> + *
> + * FINISHME: "Component packing is probably only useful for SIMD8 VS thread
> + * execution." When enabled, the correct bit must be set in 3DSTATE_VF.
> + */
> +static void
> +gen9_emit_component_packing(struct brw_context *brw)
> +{
> +   if (brw->gen < 9)
> +      return;
> +
> +   BEGIN_BATCH(5);
> +   OUT_BATCH(_3DSTATE_VF_COMPONENT_PACKING << 16 | (5 - 2));
> +   OUT_BATCH(0);
> +   OUT_BATCH(0);
> +   OUT_BATCH(0);
> +   OUT_BATCH(0);
> +   ADVANCE_BATCH();
> +}
> +
>  static void
>  gen8_emit_vertices(struct brw_context *brw)
>  {
> @@ -44,6 +71,8 @@ gen8_emit_vertices(struct brw_context *brw)
>     brw_prepare_vertices(brw);
>     brw_prepare_shader_draw_parameters(brw);
>  
> +   gen9_emit_component_packing(brw);
> +
>     if (brw->vs.prog_data->uses_vertexid || brw->vs.prog_data->uses_instanceid) {
>        unsigned vue = brw->vb.nr_enabled;
>  
> -- 
> 2.4.4
> 
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-- 
Ben Widawsky, Intel Open Source Technology Center