#include "brw_state.h"
#include "brw_defines.h"
-static void
-prepare_urb( struct brw_context *brw )
+/**
+ * When the GS is not in use, we assign the entire URB space to the VS. When
+ * the GS is in use, we split the URB space evenly between the VS and the GS.
+ * This is not ideal, but it's simple.
+ *
+ * URB size / 2 URB size / 2
+ * _____________-______________ _____________-______________
+ * / \ / \
+ * +-------------------------------------------------------------+
+ * | Vertex Shader Entries | Geometry Shader Entries |
+ * +-------------------------------------------------------------+
+ *
+ * Sandybridge GT1 has 32kB of URB space, while GT2 has 64kB.
+ * (See the Sandybridge PRM, Volume 2, Part 1, Section 1.4.7: 3DSTATE_URB.)
+ */
+void
+gen6_upload_urb(struct brw_context *brw, unsigned vs_size,
+ bool gs_present, unsigned gs_size)
{
- int nr_vs_entries;
+ int nr_vs_entries, nr_gs_entries;
+ int total_urb_size = brw->urb.size * 1024; /* in bytes */
+ const struct gen_device_info *devinfo = &brw->screen->devinfo;
- /* CACHE_NEW_VS_PROG */
- brw->urb.vs_size = MAX2(brw->vs.prog_data->urb_entry_size, 1);
+ /* Calculate how many entries fit in each stage's section of the URB */
+ if (gs_present) {
+ nr_vs_entries = (total_urb_size/2) / (vs_size * 128);
+ nr_gs_entries = (total_urb_size/2) / (gs_size * 128);
+ } else {
+ nr_vs_entries = total_urb_size / (vs_size * 128);
+ nr_gs_entries = 0;
+ }
- /* Calculate how many VS URB entries fit in the total URB size */
- nr_vs_entries = (brw->urb.size * 1024) / (brw->urb.vs_size * 128);
+ /* Then clamp to the maximum allowed by the hardware */
+ if (nr_vs_entries > devinfo->urb.max_entries[MESA_SHADER_VERTEX])
+ nr_vs_entries = devinfo->urb.max_entries[MESA_SHADER_VERTEX];
- if (nr_vs_entries > brw->urb.max_vs_entries)
- nr_vs_entries = brw->urb.max_vs_entries;
+ if (nr_gs_entries > devinfo->urb.max_entries[MESA_SHADER_GEOMETRY])
+ nr_gs_entries = devinfo->urb.max_entries[MESA_SHADER_GEOMETRY];
- /* According to volume 2a, nr_vs_entries must be a multiple of 4. */
+ /* Finally, both must be a multiple of 4 (see 3DSTATE_URB in the PRM). */
brw->urb.nr_vs_entries = ROUND_DOWN_TO(nr_vs_entries, 4);
+ brw->urb.nr_gs_entries = ROUND_DOWN_TO(nr_gs_entries, 4);
- /* Since we currently don't support Geometry Shaders, we always put the
- * GS unit in passthrough mode and don't allocate it any URB space.
- */
- brw->urb.nr_gs_entries = 0;
- brw->urb.gs_size = 1; /* Incorrect, but with 0 GS entries it doesn't matter. */
-}
-
-static void
-upload_urb(struct brw_context *brw)
-{
- struct intel_context *intel = &brw->intel;
-
- assert(brw->urb.nr_vs_entries >= 24);
+ assert(brw->urb.nr_vs_entries >=
+ devinfo->urb.min_entries[MESA_SHADER_VERTEX]);
assert(brw->urb.nr_vs_entries % 4 == 0);
assert(brw->urb.nr_gs_entries % 4 == 0);
- /* GS requirement */
- assert(!brw->gs.prog_active || brw->urb.vs_size < 5);
+ assert(vs_size <= 5);
+ assert(gs_size <= 5);
BEGIN_BATCH(3);
OUT_BATCH(_3DSTATE_URB << 16 | (3 - 2));
- OUT_BATCH(((brw->urb.vs_size - 1) << GEN6_URB_VS_SIZE_SHIFT) |
+ OUT_BATCH(((vs_size - 1) << GEN6_URB_VS_SIZE_SHIFT) |
((brw->urb.nr_vs_entries) << GEN6_URB_VS_ENTRIES_SHIFT));
- OUT_BATCH(((brw->urb.gs_size - 1) << GEN6_URB_GS_SIZE_SHIFT) |
+ OUT_BATCH(((gs_size - 1) << GEN6_URB_GS_SIZE_SHIFT) |
((brw->urb.nr_gs_entries) << GEN6_URB_GS_ENTRIES_SHIFT));
ADVANCE_BATCH();
+
+ /* From the PRM Volume 2 part 1, section 1.4.7:
+ *
+ * Because of a urb corruption caused by allocating a previous gsunit’s
+ * urb entry to vsunit software is required to send a "GS NULL
+ * Fence"(Send URB fence with VS URB size == 1 and GS URB size == 0) plus
+ * a dummy DRAW call before any case where VS will be taking over GS URB
+ * space.
+ *
+ * It is not clear exactly what this means ("URB fence" is a command that
+ * doesn't exist on Gen6). So for now we just do a full pipeline flush as
+ * a workaround.
+ */
+ if (brw->urb.gs_present && !gs_present)
+ brw_emit_mi_flush(brw);
+ brw->urb.gs_present = gs_present;
+}
+
+static void
+upload_urb(struct brw_context *brw)
+{
+ /* BRW_NEW_VS_PROG_DATA */
+ const struct brw_vue_prog_data *vs_vue_prog_data =
+ brw_vue_prog_data(brw->vs.base.prog_data);
+ const unsigned vs_size = MAX2(vs_vue_prog_data->urb_entry_size, 1);
+
+ /* BRW_NEW_GEOMETRY_PROGRAM, BRW_NEW_GS_PROG_DATA */
+ const bool gs_present =
+ brw->ff_gs.prog_active || brw->programs[MESA_SHADER_GEOMETRY];
+
+ /* Whe using GS to do transform feedback only we use the same VUE layout for
+ * VS outputs and GS outputs (as it's what the SF and Clipper expect), so we
+ * can simply make the GS URB entry size the same as for the VS. This may
+ * technically be too large in cases where we have few vertex attributes and
+ * a lot of varyings, since the VS size is determined by the larger of the
+ * two. For now, it's safe.
+ *
+ * For user-provided GS the assumption above does not hold since the GS
+ * outputs can be different from the VS outputs.
+ */
+ unsigned gs_size = vs_size;
+ if (brw->programs[MESA_SHADER_GEOMETRY]) {
+ const struct brw_vue_prog_data *gs_vue_prog_data =
+ brw_vue_prog_data(brw->gs.base.prog_data);
+ gs_size = gs_vue_prog_data->urb_entry_size;
+ assert(gs_size >= 1);
+ }
+
+ gen6_upload_urb(brw, vs_size, gs_present, gs_size);
}
const struct brw_tracked_state gen6_urb = {
.dirty = {
.mesa = 0,
- .brw = BRW_NEW_CONTEXT,
- .cache = (CACHE_NEW_VS_PROG | CACHE_NEW_GS_PROG),
+ .brw = BRW_NEW_BLORP |
+ BRW_NEW_CONTEXT |
+ BRW_NEW_FF_GS_PROG_DATA |
+ BRW_NEW_GEOMETRY_PROGRAM |
+ BRW_NEW_GS_PROG_DATA |
+ BRW_NEW_VS_PROG_DATA,
},
- .prepare = prepare_urb,
.emit = upload_urb,
};
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