From d72d8a0c735def92599a19afb973923bc6b02c9f Mon Sep 17 00:00:00 2001
From: Adrian Perez de Castro <aperez@igalia.com>
Date: Tue, 6 Feb 2024 13:20:37 +0200
Subject: [PATCH] drm: Detect if drivers support buffer modifiers

Use drmGetCap() in the DRM modesetting renderer to detect whether
framebuffers can be created with modifiers, instead of always trying
to use them and falling back to avoid them.
---
 platform/drm/cog-drm-modeset-renderer.c | 23 ++++++++++++++++-------
 platform/drm/cog-platform-drm.c         |  1 +
 2 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/platform/drm/cog-drm-modeset-renderer.c b/platform/drm/cog-drm-modeset-renderer.c
index 710ce75a..4b778941 100644
--- a/platform/drm/cog-drm-modeset-renderer.c
+++ b/platform/drm/cog-drm-modeset-renderer.c
@@ -99,6 +99,7 @@ typedef struct {
     drmModeModeInfo mode;
     bool            mode_set;
     bool            atomic_modesetting;
+    bool            addfb2_modifiers;
 
     struct {
         drmModeObjectProperties *props;
@@ -190,14 +191,13 @@ drm_create_buffer_for_bo(CogDrmModesetRenderer *self,
         in_modifiers[i] = in_modifiers[0];
     }
 
-    int flags = 0;
-    if (in_modifiers[0])
-        flags = DRM_MODE_FB_MODIFIERS;
-
+    int      ret;
     uint32_t fb_id = 0;
-    int ret = drmModeAddFB2WithModifiers(get_drm_fd(self), width, height, format, in_handles, in_strides, in_offsets,
-                                         in_modifiers, &fb_id, flags);
-    if (ret) {
+
+    if (G_LIKELY(self->addfb2_modifiers)) {
+        ret = drmModeAddFB2WithModifiers(get_drm_fd(self), width, height, format, in_handles, in_strides, in_offsets,
+                                         in_modifiers, &fb_id, DRM_MODE_FB_MODIFIERS);
+    } else {
         in_handles[0] = gbm_bo_get_handle(bo).u32;
         in_handles[1] = in_handles[2] = in_handles[3] = 0;
         in_strides[0] = gbm_bo_get_stride(bo);
@@ -661,6 +661,15 @@ cog_drm_modeset_renderer_new(struct gbm_device     *gbm_dev,
         .plane_id = plane_id,
         .atomic_modesetting = atomic_modesetting,
     };
+
+    uint64_t value = 0;
+    if (drmGetCap(gbm_device_get_fd(self->gbm_dev), DRM_CAP_ADDFB2_MODIFIERS, &value)) {
+        g_debug("%s: Cannot get addfb2_modifiers capability: %s", G_STRFUNC, g_strerror(errno));
+    } else {
+        g_debug("%s: Capability addfb2_modifiers = %#" PRIx64, G_STRFUNC, value);
+        self->addfb2_modifiers = !!value;
+    }
+
     wl_list_init(&self->buffer_list);
     memcpy(&self->mode, mode, sizeof(drmModeModeInfo));
 
diff --git a/platform/drm/cog-platform-drm.c b/platform/drm/cog-platform-drm.c
index 86e8c5ae..f2c3b9c4 100644
--- a/platform/drm/cog-platform-drm.c
+++ b/platform/drm/cog-platform-drm.c
@@ -131,6 +131,7 @@ static struct {
     double   device_scale;
 
     bool atomic_modesetting;
+    bool addfb2_modifiers;
     bool mode_set;
 } drm_data = {
     .fd = -1,