marfrit-packages/arch/chromium-fourier/patches/nv12-external-oes-on-modifier-external-only.patch

From: Markus Fritsche <mfritsche@reauktion.de>
Subject: [PATCH] gpu/ozone: pick GL_TEXTURE_EXTERNAL_OES for NV12 dmabufs whose
 DRM modifier is advertised external_only by the EGL driver
Date: 2026-04-28

Background
----------
On mainline-Linux Mali GPUs (mesa panfrost / panthor on Bifrost / Valhall)
every NV12 modifier exposed by `eglQueryDmaBufModifiersEXT` is flagged
`external_only` — DRM_FORMAT_MOD_LINEAR + ARM AFBC × 2 + ARM AFRC. Mesa's
behavior is spec-correct: GLES sampling of multi-plane formats is
defined only via `samplerExternalOES`, never `sampler2D`. The chromium
NV12 import path at
`gpu/command_buffer/service/shared_image/ozone_image_gl_textures_holder.cc`
already chooses `GL_TEXTURE_EXTERNAL_OES` when the SharedImageFormat is
flagged `PrefersExternalSampler` — but that flag is only set for the
generic "multi-plane on Linux" case in
`media/gpu/chromeos/mailbox_video_frame_converter.cc`. Frames that
arrive with an `external_only`-flagged modifier from a producer that
didn't set the flag (V4L2 hantro NV12 with AFBC/AFRC capture format on
RK3588's rkvdec2, future NativePixmap producers, etc.) hit the
`GL_TEXTURE_2D` path; ANGLE's `validationES.cpp:4894` then rejects YUV
EGLImages on non-EXTERNAL_OES targets, and the import fails.

This patch closes the gap: the texture-target choice in
`OzoneImageGLTexturesHolder::GetBinding` now consults the EGL driver's
`external_only` annotation for the pixmap's actual modifier in addition
to `format.PrefersExternalSampler()`. If either says "external sampler
required", the target switches to `GL_TEXTURE_EXTERNAL_OES`. Skia
Ganesh handles `GL_TEXTURE_EXTERNAL_OES` natively via
`GrGLTextureInfo.fTarget`, so no shader changes are required. Same
infrastructure chromium already uses for Android camera / decoder
dmabufs, retargeted at the Linux ozone layer.

Result is cached per `(fourcc, modifier)` tuple via a function-local
static `base::flat_map`, so the EGL query is not on the per-frame hot
path — once per unique format+modifier combination, after which the
runtime cost is a hash lookup behind a base::Lock.

Bug crbug.com/1498703 is the closest existing tracker; framing this
upstream as "make Linux NV12 import path consistent with the
ChromeOS PrefersExternalSampler default" is the right angle.

diff --git a/gpu/command_buffer/service/shared_image/ozone_image_gl_textures_holder.cc b/gpu/command_buffer/service/shared_image/ozone_image_gl_textures_holder.cc
index 525bdcb0dc..43b0723326 100644
--- a/gpu/command_buffer/service/shared_image/ozone_image_gl_textures_holder.cc
+++ b/gpu/command_buffer/service/shared_image/ozone_image_gl_textures_holder.cc
@@ -16,6 +16,7 @@
 #include "ui/gl/gl_bindings.h"
 #include "ui/gl/scoped_binders.h"
 #include "ui/ozone/public/gl_ozone.h"
+#include "ui/ozone/common/native_pixmap_egl_binding.h"
 #include "ui/ozone/public/native_pixmap_gl_binding.h"
 #include "ui/ozone/public/ozone_platform.h"
 #include "ui/ozone/public/surface_factory_ozone.h"
@@ -82,7 +83,14 @@ std::unique_ptr<ui::NativePixmapGLBinding> GetBinding(
   // being multiplanar (if using per-plane sampling of a multiplanar texture,
   // the buffer format passed in here must be the single-planar format of the
   // plane).
-  if (format.PrefersExternalSampler()) {
+  // chromium-fourier: also pick GL_TEXTURE_EXTERNAL_OES whenever the
+  // pixmap's DRM modifier is advertised external_only by the EGL
+  // driver. Mesa panfrost / panthor mark every NV12 modifier
+  // external_only — the PrefersExternalSampler flag alone misses
+  // the AFBC / AFRC tiled paths.
+  if (format.PrefersExternalSampler() ||
+      ui::NativePixmapEGLBinding::ModifierRequiresExternalOES(
+          pixmap.get(), plane_format)) {
     target = GL_TEXTURE_EXTERNAL_OES;
   } else {
     target = GL_TEXTURE_2D;
diff --git a/ui/ozone/common/native_pixmap_egl_binding.cc b/ui/ozone/common/native_pixmap_egl_binding.cc
index 31877f4459..6855c1093e 100644
--- a/ui/ozone/common/native_pixmap_egl_binding.cc
+++ b/ui/ozone/common/native_pixmap_egl_binding.cc
@@ -6,10 +6,13 @@
 
 #include <array>
 
+#include "base/containers/flat_map.h"
 #include "base/logging.h"
 #include "base/memory/scoped_refptr.h"
+#include "base/no_destructor.h"
 #include "base/notreached.h"
 #include "base/numerics/safe_conversions.h"
+#include "base/synchronization/lock.h"
 #include "ui/gfx/linux/drm_util_linux.h"
 #include "ui/gl/gl_bindings.h"
 #include "ui/gl/gl_surface_egl.h"
@@ -56,6 +59,75 @@ bool NativePixmapEGLBinding::IsSharedImageFormatSupported(
     viz::SharedImageFormat format) {
   return GetFourCCFormatFromSharedImageFormat(format) != DRM_FORMAT_INVALID;
 }
+// static
+bool NativePixmapEGLBinding::ModifierRequiresExternalOES(
+    const gfx::NativePixmap* pixmap,
+    viz::SharedImageFormat format) {
+  // chromium-fourier: query the EGL driver for the (fourcc, modifier)
+  // tuple's external_only flag. Cache results — eglQueryDmaBufModifiersEXT
+  // is a synchronous round-trip into the driver and we want it off the
+  // per-frame hot path. The cache lives for the lifetime of the GPU
+  // process (modifier tables don't change after EGL init).
+  if (!pixmap) {
+    return false;
+  }
+  const uint64_t modifier = pixmap->GetFormatModifier();
+  if (modifier == gfx::NativePixmapHandle::kNoModifier) {
+    // Implicit linear — same answer the driver would give for the
+    // matching LINEAR entry, but cheaper not to query.
+    return false;
+  }
+  const uint32_t fourcc = GetFourCCFormatFromSharedImageFormat(format);
+  if (fourcc == DRM_FORMAT_INVALID) {
+    return false;
+  }
+
+  using Key = std::pair<uint32_t, uint64_t>;
+  static base::NoDestructor<base::Lock> cache_lock;
+  static base::NoDestructor<base::flat_map<Key, bool>> cache;
+  {
+    base::AutoLock lock(*cache_lock);
+    auto it = cache->find({fourcc, modifier});
+    if (it != cache->end()) {
+      return it->second;
+    }
+  }
+
+  bool external_only = false;
+  do {
+    auto* display = gl::GLSurfaceEGL::GetGLDisplayEGL();
+    if (!display || !display->ext->b_EGL_EXT_image_dma_buf_import_modifiers) {
+      break;
+    }
+    EGLDisplay egl_display = display->GetDisplay();
+    EGLint num_modifiers = 0;
+    if (!eglQueryDmaBufModifiersEXT(egl_display, fourcc, 0, nullptr, nullptr,
+                                    &num_modifiers) ||
+        num_modifiers <= 0) {
+      break;
+    }
+    std::vector<EGLuint64KHR> modifiers(num_modifiers);
+    std::vector<EGLBoolean> ext_only(num_modifiers);
+    if (!eglQueryDmaBufModifiersEXT(egl_display, fourcc, num_modifiers,
+                                    modifiers.data(), ext_only.data(),
+                                    &num_modifiers)) {
+      break;
+    }
+    for (EGLint i = 0; i < num_modifiers; ++i) {
+      if (modifiers[i] == modifier) {
+        external_only = (ext_only[i] == EGL_TRUE);
+        break;
+      }
+    }
+  } while (0);
+
+  {
+    base::AutoLock lock(*cache_lock);
+    cache->insert_or_assign({fourcc, modifier}, external_only);
+  }
+  return external_only;
+}
+
 
 // static
 std::unique_ptr<NativePixmapGLBinding> NativePixmapEGLBinding::Create(
diff --git a/ui/ozone/common/native_pixmap_egl_binding.h b/ui/ozone/common/native_pixmap_egl_binding.h
index 61fb0de77f..ad3ac9ced5 100644
--- a/ui/ozone/common/native_pixmap_egl_binding.h
+++ b/ui/ozone/common/native_pixmap_egl_binding.h
@@ -27,6 +27,17 @@ class NativePixmapEGLBinding : public NativePixmapGLBinding {
 
   static bool IsSharedImageFormatSupported(viz::SharedImageFormat format);
 
+  // chromium-fourier: returns true when |pixmap|'s DRM format modifier
+  // is advertised by the EGL driver as `external_only` for the given
+  // SharedImage format. Used at SharedImage creation time to override
+  // the default GL_TEXTURE_2D target to GL_TEXTURE_EXTERNAL_OES so that
+  // mesa panfrost / panthor NV12 dmabufs (always external_only) import
+  // cleanly via glEGLImageTargetTexture2DOES + samplerExternalOES.
+  // Result is cached per (fourcc, modifier) tuple — the underlying
+  // eglQueryDmaBufModifiersEXT call is not on the per-frame hot path.
+  static bool ModifierRequiresExternalOES(const gfx::NativePixmap* pixmap,
+                                          viz::SharedImageFormat format);
+
   // Create an EGLImage from a given NativePixmap and plane and bind
   // |texture_id| to |target| followed by binding the image to |target|. The
   // color space is for the external sampler: When we sample the YUV buffer as