Mesa (main): st/mesa: always report the max samples as supported

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Module: Mesa
Branch: main
Commit: 561f9ae74b2b7da06bb4830aaca8d017a3dd2746
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=561f9ae74b2b7da06bb4830aaca8d017a3dd2746

Author: Ilia Mirkin <imirkin at alum.mit.edu>
Date:   Tue Jun 15 00:49:02 2021 -0400

st/mesa: always report the max samples as supported

This is required by GL. Doing this even when the backend driver does not
support it leads to creating attachments which are not renderable. This
is not ideal, but does pass tests. This covers scenarios such as missing
MSAA for 128-bit formats on Sandybridge, and missing 8x MSAA on 128-bit
formats on NVIDIA Tesla generation boards.

Signed-off-by: Ilia Mirkin <imirkin at alum.mit.edu>
Reviewed-by: Marek Olšák <marek.olsak at amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/11372>

---

 src/mesa/state_tracker/st_format.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/mesa/state_tracker/st_format.c b/src/mesa/state_tracker/st_format.c
index d21e916808c..381c01bbac8 100644
--- a/src/mesa/state_tracker/st_format.c
+++ b/src/mesa/state_tracker/st_format.c
@@ -1392,6 +1392,7 @@ st_QuerySamplesForFormat(struct gl_context *ctx, GLenum target,
    struct st_context *st = st_context(ctx);
    enum pipe_format format;
    unsigned i, bind, num_sample_counts = 0;
+   unsigned min_max_samples;
 
    (void) target;
 
@@ -1400,6 +1401,13 @@ st_QuerySamplesForFormat(struct gl_context *ctx, GLenum target,
    else
       bind = PIPE_BIND_RENDER_TARGET;
 
+   if (_mesa_is_enum_format_integer(internalFormat))
+      min_max_samples = ctx->Const.MaxIntegerSamples;
+   else if (_mesa_is_depth_or_stencil_format(internalFormat))
+      min_max_samples = ctx->Const.MaxDepthTextureSamples;
+   else
+      min_max_samples = ctx->Const.MaxColorTextureSamples;
+
    /* If an sRGB framebuffer is unsupported, sRGB formats behave like linear
     * formats.
     */
@@ -1413,7 +1421,7 @@ st_QuerySamplesForFormat(struct gl_context *ctx, GLenum target,
                                 PIPE_TEXTURE_2D, i, i, bind,
                                 false, false);
 
-      if (format != PIPE_FORMAT_NONE) {
+      if (format != PIPE_FORMAT_NONE || i == min_max_samples) {
          samples[num_sample_counts++] = i;
       }
    }