asahi: Allow explicit non-LINEAR modifiers for scanout

The compositor is responsible for picking the right supported modifiers
for scanout. If we get no modifiers, we have to assume linear, but if we
do, just roll with it and don't attempt to force things.

Signed-off-by: Asahi Lina <lina@asahilina.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/22353>

src/gallium/drivers/asahi/agx_pipe.c

@@ -372,8 +372,7 @@ static bool
 agx_twiddled_allowed(const struct agx_resource *pres)
 {
    /* Certain binds force linear */
-   if (pres->base.bind &
-       (PIPE_BIND_DISPLAY_TARGET | PIPE_BIND_SCANOUT | PIPE_BIND_LINEAR))
+   if (pres->base.bind & (PIPE_BIND_DISPLAY_TARGET | PIPE_BIND_LINEAR))
       return false;
 
    /* Buffers must be linear */
@@ -464,6 +463,14 @@ agx_select_best_modifier(const struct agx_resource *pres)
    if (agx_linear_allowed(pres) && pres->base.usage == PIPE_USAGE_STAGING)
       return DRM_FORMAT_MOD_LINEAR;
 
+   /* For SCANOUT resources with no explicit modifier selection, assume we need
+    * linear.
+    */
+   if (pres->base.bind & PIPE_BIND_SCANOUT) {
+      assert(agx_linear_allowed(pres));
+      return DRM_FORMAT_MOD_LINEAR;
+   }
+
    if (agx_twiddled_allowed(pres)) {
       if (agx_compression_allowed(pres))
          return DRM_FORMAT_MOD_APPLE_TWIDDLED_COMPRESSED;