[Mesa-dev] [PATCH] egl/surfaceless: Use KMS swrast fallback

[gurchetansingh at chromium.org]

From: Gurchetan Singh <gurchetansingh at chromium.org>

The kms_swrast extension is an actively developed software fallback,
and platform_surfaceless can use it if there are no available
hardware drivers.
---
 src/egl/drivers/dri2/platform_surfaceless.c | 77 ++++++++++++++++++-----------
 1 file changed, 48 insertions(+), 29 deletions(-)

diff --git a/src/egl/drivers/dri2/platform_surfaceless.c b/src/egl/drivers/dri2/platform_surfaceless.c
index 3c00ff44ab..518b74fcde 100644
--- a/src/egl/drivers/dri2/platform_surfaceless.c
+++ b/src/egl/drivers/dri2/platform_surfaceless.c
@@ -267,6 +267,47 @@ static const __DRIextension *image_loader_extensions[] = {
    NULL,
 };
 
+static int
+surfaceless_probe_device(_EGLDisplay *dpy, int swrast)
+{
+   struct dri2_egl_display *dri2_dpy = dpy->DriverData;
+   const int limit = 64;
+   const int base = 128;
+   int fd;
+   int i;
+
+   for (i = 0; i < limit; ++i) {
+      char *card_path;
+      if (asprintf(&card_path, DRM_RENDER_DEV_NAME, DRM_DIR_NAME, base + i) < 0)
+         continue;
+
+      fd = loader_open_device(card_path);
+      free(card_path);
+      if (fd < 0)
+         continue;
+
+      if (swrast)
+         dri2_dpy->driver_name = strdup("kms_swrast");
+      else
+         dri2_dpy->driver_name = loader_get_driver_for_fd(fd);
+      if (!dri2_dpy->driver_name) {
+         close(fd);
+         continue;
+      }
+
+      dri2_dpy->fd = fd;
+      if (dri2_load_driver_dri3(dpy))
+         return 0;
+
+      close(fd);
+      dri2_dpy->fd = -1;
+      free(dri2_dpy->driver_name);
+      dri2_dpy->driver_name = NULL;
+   }
+
+   return -1;
+}
+
 EGLBoolean
 dri2_initialize_surfaceless(_EGLDriver *drv, _EGLDisplay *disp)
 {
@@ -282,36 +323,14 @@ dri2_initialize_surfaceless(_EGLDriver *drv, _EGLDisplay *disp)
 
    dri2_dpy->fd = -1;
    disp->DriverData = (void *) dri2_dpy;
-
-   const int limit = 64;
-   const int base = 128;
-   for (int i = 0; i < limit; ++i) {
-      char *card_path;
-      if (asprintf(&card_path, DRM_RENDER_DEV_NAME, DRM_DIR_NAME, base + i) < 0)
-         continue;
-
-      dri2_dpy->fd = loader_open_device(card_path);
-
-      free(card_path);
-      if (dri2_dpy->fd < 0)
-         continue;
-
-      dri2_dpy->driver_name = loader_get_driver_for_fd(dri2_dpy->fd);
-      if (dri2_dpy->driver_name) {
-         if (dri2_load_driver_dri3(disp)) {
-            driver_loaded = 1;
-            break;
-         }
-         free(dri2_dpy->driver_name);
-         dri2_dpy->driver_name = NULL;
+   if (surfaceless_probe_device(disp, 0) < 0) {
+         _eglLog(_EGL_DEBUG, "No hardware driver found, falling back to"
+	         "kms_swrast");
+      /* Retry with kms_swrast driver. */
+      if (surfaceless_probe_device(disp, 1) < 0) {
+         err = "DRI2: failed to load driver";
+         goto cleanup;
       }
-      close(dri2_dpy->fd);
-      dri2_dpy->fd = -1;
-   }
-
-   if (!driver_loaded) {
-      err = "DRI2: failed to load driver";
-      goto cleanup;
    }
 
    dri2_dpy->loader_extensions = image_loader_extensions;
-- 
2.12.2