panfrost: Flip point coords in hardware

On Bifrost, this is very easy: there's an RSD bit to Y-flip gl_PointCoord. It
should map perfectly to the Gallium bit. With this change, we no longer use
lower_pntc_ytransform on Bifrost, saving a bit of ALU when reading point
coordinates.

On Valhall, this is quite hard: the bit is in the framebuffer descriptor now!
That means it can't be changed in a batch. This is expected to be ok: on GLES
and VK, the origin is controlled only by the framebuffer orientation. It's a
bigger problem on big GL, where GL_POINT_SPRITE_COORD_ORIGIN can be set freely.
To cope, a tri-state data structure is used for the state tracking. This has a
failure case on Valhall: every draw toggling the coord origin. However, the
intention of the ORIGIN state bit is smoothing over coordinate system
differences; it should never /actually/ change once set. Until we see an app
doing something so stupid, I don't think we should worry about.

We need all the Valhall tri-state infrastructure for handling provoking vertices
on big GL anyway.

Signed-off-by: Alyssa Rosenzweig <alyssa@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16173>

src/gallium/drivers/panfrost/pan_cmdstream.c

@@ -573,6 +573,13 @@ panfrost_prepare_fs_state(struct panfrost_context *ctx,
                         cfg.multisample_misc.evaluate_per_sample = true;
                         cfg.preload.fragment.sample_mask_id = true;
                 }
+
+                /* Flip gl_PointCoord (and point sprites) depending on API
+                 * setting on framebuffer orientation. We do not use
+                 * lower_wpos_pntc on Bifrost.
+                 */
+                cfg.properties.point_sprite_coord_origin_max_y =
+                        (rast->sprite_coord_mode == PIPE_SPRITE_COORD_LOWER_LEFT);
 #endif
 
                 cfg.stencil_mask_misc.alpha_to_coverage = alpha_to_coverage;
@@ -3780,6 +3787,21 @@ panfrost_indirect_draw(struct panfrost_batch *batch,
 }
 #endif
 
+static bool
+panfrost_compatible_batch_state(struct panfrost_batch *batch)
+{
+        /* Only applies on Valhall */
+        if (PAN_ARCH < 9)
+                return true;
+
+        struct panfrost_context *ctx = batch->ctx;
+        struct pipe_rasterizer_state *rast = &ctx->rasterizer->base;
+
+        bool coord = (rast->sprite_coord_mode == PIPE_SPRITE_COORD_LOWER_LEFT);
+
+        return pan_tristate_set(&batch->sprite_coord_origin, coord);
+}
+
 static void
 panfrost_draw_vbo(struct pipe_context *pipe,
                   const struct pipe_draw_info *info,
@@ -3810,6 +3832,9 @@ panfrost_draw_vbo(struct pipe_context *pipe,
         if (unlikely(batch->scoreboard.job_index > 10000))
                 batch = panfrost_get_fresh_batch_for_fbo(ctx, "Too many draws");
 
+        if (unlikely(!panfrost_compatible_batch_state(batch)))
+                batch = panfrost_get_fresh_batch_for_fbo(ctx, "State change");
+
         /* panfrost_batch_skip_rasterization reads
          * batch->scissor_culls_everything, which is set by
          * panfrost_emit_viewport, so call that first.
@@ -4371,14 +4396,7 @@ prepare_shader(struct panfrost_shader_state *state,
         pan_pack(out, RENDERER_STATE, cfg) {
                 pan_shader_prepare_rsd(&state->info, state->bin.gpu, &cfg);
 
-#if PAN_ARCH >= 6
-                /* Match the mesa/st convention. If this needs to be flipped,
-                 * nir_lower_pntc_ytransform will do so.
-                 */
-                if (state->info.stage == MESA_SHADER_FRAGMENT)
-                        cfg.properties.point_sprite_coord_origin_max_y = true;
-#endif
-        }
+       }
 #else
         assert(upload);
 

src/gallium/drivers/panfrost/pan_job.c

@@ -435,6 +435,7 @@ panfrost_batch_to_fb_info(const struct panfrost_batch *batch,
         fb->extent.maxy = batch->maxy - 1;
         fb->nr_samples = util_framebuffer_get_num_samples(&batch->key);
         fb->rt_count = batch->key.nr_cbufs;
+        fb->sprite_coord_origin = pan_tristate_get(batch->sprite_coord_origin);
 
         static const unsigned char id_swz[] = {
                 PIPE_SWIZZLE_X, PIPE_SWIZZLE_Y, PIPE_SWIZZLE_Z, PIPE_SWIZZLE_W,

src/gallium/drivers/panfrost/pan_job.h

@@ -33,6 +33,52 @@
 #include "pan_resource.h"
 #include "pan_scoreboard.h"
 
+/* Simple tri-state data structure. In the default "don't care" state, the value
+ * may be set to true or false. However, once the value is set, it must not be
+ * changed. Declared inside of a struct to prevent casting to bool, which is an
+ * error. The getter needs to be used instead.
+ */
+struct pan_tristate {
+        enum {
+                PAN_TRISTATE_DONTCARE,
+                PAN_TRISTATE_FALSE,
+                PAN_TRISTATE_TRUE,
+        } v;
+};
+
+/*
+ * Try to set a tristate value to a desired boolean value. Returns whether the
+ * operation is successful.
+ */
+static bool
+pan_tristate_set(struct pan_tristate *state, bool value)
+{
+        switch (state->v) {
+        case PAN_TRISTATE_DONTCARE:
+                state->v = value ? PAN_TRISTATE_TRUE : PAN_TRISTATE_FALSE;
+                return true;
+
+        case PAN_TRISTATE_FALSE:
+                return (value == false);
+
+        case PAN_TRISTATE_TRUE:
+                return (value == true);
+
+        default:
+                unreachable("Invalid tristate value");
+        }
+}
+
+/*
+ * Read the boolean value of a tristate. Return value undefined in the don't
+ * care state.
+ */
+static bool
+pan_tristate_get(struct pan_tristate state)
+{
+        return (state.v == PAN_TRISTATE_TRUE);
+}
+
 /* A panfrost_batch corresponds to a bound FBO we're rendering to,
  * collecting over multiple draws. */
 
@@ -141,6 +187,11 @@ struct panfrost_batch {
          */
         mali_ptr images[PIPE_SHADER_TYPES];
 
+        /* On Valhall, these are properties of the batch. On Bifrost, they are
+         * per draw.
+         */
+        struct pan_tristate sprite_coord_origin;
+
         /* Referenced resources */
         struct set *resources;
 };

src/panfrost/bifrost/bifrost_compile.h

@@ -48,7 +48,6 @@ static const nir_shader_compiler_options bifrost_nir_options = {
         .lower_fdph = true,
         .lower_fsqrt = true,
 
-        .lower_wpos_pntc = true,
         .lower_fsign = true,
 
         .lower_bitfield_insert_to_shifts = true,

src/panfrost/lib/pan_cs.c

@@ -690,6 +690,10 @@ GENX(pan_emit_fbd)(const struct panfrost_device *dev,
 
                         *valid |= full;
                 }
+
+#if PAN_ARCH >= 9
+                cfg.point_sprite_coord_origin_max_y = fb->sprite_coord_origin;
+#endif
         }
 
 #if PAN_ARCH >= 6

src/panfrost/lib/pan_cs.h

@@ -117,6 +117,9 @@ struct pan_fb_info {
         union {
                 struct pan_fb_bifrost_info bifrost;
         };
+
+        /* Only used on Valhall */
+        bool sprite_coord_origin;
 };
 
 static inline unsigned