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

[Eric Engestrom]

On Friday, 2017-09-29 23:57:32 +0000, gurchetansingh at chromium.org wrote:
> 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)

both the `swrast` param and the return value are ints used as bools.
please change those to proper `bool`

> +{
> +   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");

To keep in line with other platforms, please check LIBGL_ALWAYS_SOFTWARE
as well.

Look at dri2_initialize_x11() for example, or dri2_initialize_wayland()
after my patch:
https://lists.freedesktop.org/archives/mesa-dev/2017-October/171295.html

> +      /* 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
>