drm/asahi: g17: add g17_tvb_min_blocks to pre-size the tiler heap

drivers/gpu/drm/asahi/asahi_core.rs

@@ -130,6 +130,10 @@ module! {
             default: 1,
             description: "Count held GPU memory in its creator's RSS for the OOM killer (1 = on)",
         },
+        g17_tvb_min_blocks: usize {
+            default: 0,
+            description: "G17: floor on a render target's initial TVB blocks (0: use the computed tile-count size). 25G83 is always floored to at least 256, because its firmware's mid-render TVB growth trips a forward-progress watchdog (reason 0); this parameter overrides the floor on any G17 part",
+        },
         g16_deadline_ms: u32 {
             default: 5000,
             description: "G16: administrative completion-stamp deadline, ms (0 disables; long running work can exceed it)",

drivers/gpu/drm/asahi/g17/buffer/target.rs

@@ -105,6 +105,13 @@ impl Layout {
             );
         }
         tvb_blocks = tvb_blocks.max(cfg::TVB_INITIAL_PAGES.len());
+        // 25G83 firmware hangs if asked to grow the TVB mid-render (reason-0 watchdog), so
+        // pre-size it past ordinary overflow. Other G17 parts grow reliably and keep their
+        // computed size; the module parameter overrides the floor on any part.
+        let min_blocks = crate::module_parameters::g17_tvb_min_blocks
+            .value()
+            .max(if programs == RegisterPrograms::V25G83 { 256 } else { 0 });
+        tvb_blocks = tvb_blocks.max(min_blocks.min(cfg::TVB_MAX_BLOCKS));
         let mut gtp = [None; 8];
         let mut tpc_end = tpc_size;
         if programs == RegisterPrograms::V25G83 {