[Mesa-dev] [PATCH] egl/dri2: implement platform_null.

[Emil Velikov]

Hi Haixia Shi,

On 22/01/15 17:35, Haixia Shi wrote:
> Try the render node first and use it if available. Otherwise fall back to
> normal nodes.
> 
What is the use-case for such a platform - I assume it's worth
mentioning in the commit message ?

No other platform picks the device at random as seen below. Why did you
choose such an approach ? It seems like one can easily shoot themselves
by using it.

...
> diff --git a/src/egl/drivers/dri2/platform_null.c b/src/egl/drivers/dri2/platform_null.c
> new file mode 100644
> index 0000000..4f0b18f
> --- /dev/null
> +++ b/src/egl/drivers/dri2/platform_null.c
...
> +static const char* node_path_fmt_card = "/dev/dri/card%d";
You can reuse the DRM_DIR_NAME + DRM_DEV_NAME macros (from xf86drm.h)
for this.

> +static const char* node_path_fmt_render = "/dev/dri/renderD%d";
There is no macro for the renderD%d, although you can still use
DRM_DIR_NAME for the path.

> +
> +EGLBoolean
> +dri2_initialize_null(_EGLDriver *drv, _EGLDisplay *disp)
> +{
> +   struct dri2_egl_display *dri2_dpy;
> +   const char* err;
> +   int i, render_node;
> +   int driver_loaded = 0;
> +
> +   loader_set_logger(_eglLog);
> +
> +   dri2_dpy = calloc(1, sizeof *dri2_dpy);
> +   if (!dri2_dpy)
> +      return _eglError(EGL_BAD_ALLOC, "eglInitialize");
> +
> +   disp->DriverData = (void *) dri2_dpy;
> +
> +   for (render_node = 1; render_node >= 0; --render_node) {
> +      const char* node_path_fmt =
> +            render_node ? node_path_fmt_render : node_path_fmt_card;
> +      const int base = render_node ? 128 : 0;
> +      for (i = 0; i < 16; ++i) {
What was the reason behind choosing 16 here ?

> +         char *card_path;
> +         if (asprintf(&card_path, node_path_fmt, base + i) < 0)
> +            continue;
> +
> +         dri2_dpy->fd = open(card_path, O_RDWR);
If you open a normal node (card%d) I believe that you'll need an
authenticate hook in dri2_egl_display_vtbl. Does things work without it
on your system/platform ?

Cheers
Emil