freedreno/a6xx: Fix buffer size clamping

Fixes spec@arb_texture_buffer_object@texture-buffer-size-clamp@* which
we start hitting after exposing glsl420

Signed-off-by: Rob Clark <robdclark@chromium.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/19236>

src/gallium/drivers/freedreno/a6xx/fd6_image.c

@@ -34,6 +34,7 @@
 
 #include "fd6_image.h"
 #include "fd6_resource.h"
+#include "fd6_screen.h"
 #include "fd6_texture.h"
 
 static const uint8_t swiz_identity[4] = {PIPE_SWIZZLE_X, PIPE_SWIZZLE_Y,
@@ -88,11 +89,15 @@ fd6_emit_image_descriptor(struct fd_context *ctx, struct fd_ringbuffer *ring, co
    }
 
    if (buf->resource->target == PIPE_BUFFER) {
-   uint32_t descriptor[FDL6_TEX_CONST_DWORDS];
+      uint32_t descriptor[FDL6_TEX_CONST_DWORDS];
+
+      uint32_t size = fd_clamp_buffer_size(buf->format, buf->u.buf.size,
+                                           A4XX_MAX_TEXEL_BUFFER_ELEMENTS_UINT);
+
       fdl6_buffer_view_init(descriptor, buf->format, swiz_identity,
                            buf->u.buf.offset, /* Using relocs for addresses */
-                           buf->u.buf.size);
-   fd6_emit_single_plane_descriptor(ring, buf->resource, descriptor);
+                           size);
+      fd6_emit_single_plane_descriptor(ring, buf->resource, descriptor);
    } else {
       struct fdl_view_args args = {
          /* Using relocs for addresses */

src/gallium/drivers/freedreno/a6xx/fd6_texture.c

@@ -37,6 +37,7 @@
 #include "freedreno_dev_info.h"
 #include "fd6_emit.h"
 #include "fd6_resource.h"
+#include "fd6_screen.h"
 #include "fd6_texture.h"
 
 static void
@@ -233,8 +234,10 @@ fd6_sampler_view_update(struct fd_context *ctx,
       /* Using relocs for addresses still */
       uint64_t iova = cso->u.buf.offset;
 
-      fdl6_buffer_view_init(so->descriptor, cso->format, swiz, iova,
-                            cso->u.buf.size);
+      uint32_t size = fd_clamp_buffer_size(cso->format, cso->u.buf.size,
+                                           A4XX_MAX_TEXEL_BUFFER_ELEMENTS_UINT);
+
+      fdl6_buffer_view_init(so->descriptor, cso->format, swiz, iova, size);
    } else {
       struct fdl_view_args args = {
          /* Using relocs for addresses still */

src/gallium/drivers/freedreno/freedreno_screen.c

@@ -292,14 +292,15 @@ fd_screen_get_param(struct pipe_screen *pscreen, enum pipe_cap param)
        * splitting high bits of index into 2nd dimension..
        */
       if (is_a3xx(screen))
-         return 8192;
+         return A3XX_MAX_TEXEL_BUFFER_ELEMENTS_UINT;
 
       /* Note that the Vulkan blob on a540 and 640 report a
        * maxTexelBufferElements of just 65536 (the GLES3.2 and Vulkan
        * minimum).
        */
       if (is_a4xx(screen) || is_a5xx(screen) || is_a6xx(screen))
-         return 1 << 27;
+         return A4XX_MAX_TEXEL_BUFFER_ELEMENTS_UINT;
+
       return 0;
 
    case PIPE_CAP_TEXTURE_FLOAT_LINEAR:

src/gallium/drivers/freedreno/freedreno_util.h

@@ -442,6 +442,31 @@ fd_msaa_samples(unsigned samples)
    }
 }
 
+#define A3XX_MAX_TEXEL_BUFFER_ELEMENTS_UINT (1 << 13)
+
+/* Note that the Vulkan blob on a540 and 640 report a
+ * maxTexelBufferElements of just 65536 (the GLES3.2 and Vulkan
+ * minimum).
+ */
+#define A4XX_MAX_TEXEL_BUFFER_ELEMENTS_UINT (1 << 27)
+
+static inline uint32_t
+fd_clamp_buffer_size(enum pipe_format format, uint32_t size,
+                     unsigned max_texel_buffer_elements)
+{
+   /* The spec says:
+    *    The number of texels in the texel array is then clamped to the value of
+    *    the implementation-dependent limit GL_MAX_TEXTURE_BUFFER_SIZE.
+    *
+    * So compute the number of texels, compare to GL_MAX_TEXTURE_BUFFER_SIZE and update it.
+    */
+   unsigned blocksize = util_format_get_blocksize(format);
+   unsigned elements = MIN2(max_texel_buffer_elements, size / blocksize);
+
+   return elements * blocksize;
+}
+
+
 /*
  * a4xx+ helpers:
  */