etnaviv: rewrite sampler TS check

The current way this check is written is getting hard to read. Make
things a bit more verbose by splitting the checks and putting the
comments directly in front of them.

No functional change, GCC11 generates exactly the same machine code
before and after the change.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/18045>

src/gallium/drivers/etnaviv/etnaviv_texture.c

@@ -119,27 +119,41 @@ etna_configure_sampler_ts(struct etna_sampler_ts *sts, struct pipe_sampler_view
 static bool
 etna_can_use_sampler_ts(struct pipe_sampler_view *view, int num)
 {
-    /* Can use sampler TS when:
-     * - the hardware supports sampler TS.
-     * - the sampler view will be bound to sampler <VIVS_TS_SAMPLER__LEN.
-     *   HALTI5 adds a mapping from sampler to sampler TS unit, but this is AFAIK
-     *   absent on earlier models.
-     * - it is a texture, not a buffer.
-     * - the sampler view has a supported format for sampler TS.
-     * - the sampler will have one LOD, and it happens to be level 0.
-     *   (it is not sure if the hw supports it for other levels, but available
-     *   state strongly suggests only one at a time).
-     * - the resource TS is valid for level 0.
-     */
    struct etna_resource *rsc = etna_resource(view->texture);
    struct etna_screen *screen = etna_screen(rsc->base.screen);
 
-   return VIV_FEATURE(screen, chipMinorFeatures2, TEXTURE_TILED_READ) &&
-      num < VIVS_TS_SAMPLER__LEN &&
-      rsc->base.target != PIPE_BUFFER &&
-      (rsc->levels[0].ts_compress_fmt < 0 || screen->specs.v4_compression) &&
-      view->u.tex.first_level == 0 && MIN2(view->u.tex.last_level, rsc->base.last_level) == 0 &&
-      rsc->levels[0].ts_valid;
+   /* Sampler TS can be used under the following conditions: */
+
+   /* The hardware supports it. */
+   if (!VIV_FEATURE(screen, chipMinorFeatures2, TEXTURE_TILED_READ))
+      return false;
+
+   /* The sampler view will be bound to sampler < VIVS_TS_SAMPLER__LEN.
+    * HALTI5 adds a mapping from sampler to sampler TS unit, but this is AFAIK
+    * absent on earlier models. */
+   if (num >= VIVS_TS_SAMPLER__LEN)
+      return false;
+
+   /* It is a texture, not a buffer. */
+   if (rsc->base.target == PIPE_BUFFER)
+      return false;
+
+   /* Does not use compression or the hardware supports V4 compression. */
+   if (rsc->levels[0].ts_compress_fmt >= 0 && !screen->specs.v4_compression)
+      return false;
+
+   /* The sampler will have one LOD, and it happens to be level 0.
+    * (It is not sure if the hw supports it for other levels, but available
+    *  state strongly suggests only one at a time). */
+   if (view->u.tex.first_level != 0 ||
+       MIN2(view->u.tex.last_level, rsc->base.last_level) != 0)
+      return false;
+
+   /* The resource TS is valid for level 0. */
+   if (!rsc->levels[0].ts_valid)
+      return false;
+
+   return true;
 }
 
 void