video: probe format of primary plane in drm/egl context

We need to support hardware/drivers which do not support ARGB8888 in
their primary plane.

We also use p->primary_plane_format when creating the gbm surface, to
make sure it always matches (in actuality there should be little
difference).

video/out/opengl/context_drm_egl.c

@@ -25,6 +25,7 @@
 #include <unistd.h>
 
 #include <gbm.h>
+#include <drm_fourcc.h>
 #include <EGL/egl.h>
 #include <EGL/eglext.h>
 
@@ -71,6 +72,8 @@ struct priv {
     struct gbm gbm;
     struct framebuffer *fb;
 
+    uint32_t primary_plane_format;
+
     bool active;
     bool waiting_for_flip;
 
@@ -122,7 +125,7 @@ static bool init_gbm(struct ra_ctx *ctx)
         p->gbm.device,
         p->kms->mode.hdisplay,
         p->kms->mode.vdisplay,
-        GBM_FORMAT_XRGB8888,
+        p->primary_plane_format, // drm_fourcc.h defs should be gbm-compatible
         GBM_BO_USE_SCANOUT | GBM_BO_USE_RENDERING);
     if (!p->gbm.surface) {
         MP_ERR(ctx->vo, "Failed to create GBM surface.\n");
@@ -155,8 +158,13 @@ static void update_framebuffer_from_bo(struct ra_ctx *ctx, struct gbm_bo *bo)
     uint32_t stride = gbm_bo_get_stride(bo);
     uint32_t handle = gbm_bo_get_handle(bo).u32;
 
-    int ret = drmModeAddFB(fb->fd, fb->width, fb->height,
-                           32, 32, stride, handle, &fb->id);
+    int ret = drmModeAddFB2(fb->fd, fb->width, fb->height,
+                            p->primary_plane_format,
+                            (uint32_t[4]){handle, 0, 0, 0},
+                            (uint32_t[4]){stride, 0, 0, 0},
+                            (uint32_t[4]){0, 0, 0, 0},
+                            &fb->id, 0);
+
     if (ret) {
         MP_ERR(ctx->vo, "Failed to create framebuffer: %s\n", mp_strerror(errno));
     }
@@ -328,6 +336,49 @@ static void drm_egl_uninit(struct ra_ctx *ctx)
     }
 }
 
+// If primary plane supports ARGB8888 we want to use that, but if it doesn't we
+// fall back on XRGB8888. If the driver does not support atomic there is no
+// particular reason to be using ARGB8888, so we fall back to XRGB8888 (another
+// reason is that we do not have the convenient atomic_ctx and its convenient
+// primary_plane field).
+static bool probe_primary_plane_format(struct ra_ctx *ctx)
+{
+    struct priv *p = ctx->priv;
+    if (!p->kms->atomic_context) {
+        p->primary_plane_format = DRM_FORMAT_XRGB8888;
+        MP_VERBOSE(ctx->vo, "Not using DRM Atomic: Use DRM_FORMAT_XRGB8888 for primary plane.\n");
+        return true;
+    }
+
+    drmModePlane *drmplane =
+        drmModeGetPlane(p->kms->fd, p->kms->atomic_context->primary_plane->id);
+    bool have_argb8888 = false;
+    bool have_xrgb8888 = false;
+    bool result = false;
+    for (unsigned int i = 0; i < drmplane->count_formats; ++i) {
+        if (drmplane->formats[i] == DRM_FORMAT_ARGB8888) {
+            have_argb8888 = true;
+        } else if (drmplane->formats[i] == DRM_FORMAT_XRGB8888) {
+            have_xrgb8888 = true;
+        }
+    }
+
+    if (have_argb8888) {
+        p->primary_plane_format = DRM_FORMAT_ARGB8888;
+        MP_VERBOSE(ctx->vo, "DRM_FORMAT_ARGB8888 supported by primary plane.\n");
+        result = true;
+    } else if (have_xrgb8888) {
+        p->primary_plane_format = DRM_FORMAT_XRGB8888;
+        MP_VERBOSE(ctx->vo,
+                   "DRM_FORMAT_ARGB8888 not supported by primary plane: "
+                   "Falling back to DRM_FORMAT_XRGB8888.\n");
+        result = true;
+    }
+
+    drmModeFreePlane(drmplane);
+    return result;
+}
+
 static bool drm_egl_init(struct ra_ctx *ctx)
 {
     if (ctx->opts.probing) {
@@ -355,6 +406,11 @@ static bool drm_egl_init(struct ra_ctx *ctx)
         return false;
     }
 
+    if (!probe_primary_plane_format(ctx)) {
+        MP_ERR(ctx->vo, "No suitable format found on DRM primary plane.\n");
+        return false;
+    }
+
     if (!init_gbm(ctx)) {
         MP_ERR(ctx->vo, "Failed to setup GBM.\n");
         return false;