[Mesa-dev] [RFC] egl/android: Add DRM node probing and filtering

[Rob Herring]

On Wed, Apr 18, 2018 at 11:03 AM, Robert Foss <robert.foss at collabora.com> wrote:
> This patch both adds support for probing & filtering DRM nodes
> and switches away from using the GRALLOC_MODULE_PERFORM_GET_DRM_FD
> gralloc call.
>
> Currently the filtering is based just on the driver name,
> and the desired name is supplied using the "drm.gpu.vendor_name"
> Android property.
>
> The filtering itself is done using the newly introduced
> libdrm drmHandleMatch() call.
>
> Signed-off-by: Robert Foss <robert.foss at collabora.com>
> ---
>
> This patch is based on[1], which contains a new libdrm function,
> called drmHandleMatch(), which allows for matching an opened
> drm node handle against some desired properties.
>
> A choice that was made for this patch was to add support for
> falling back to to DRM nodes that have failed the filtering,
> if no node passes the filter.
> If this wouldn't be useful to anyone, I would suggest ripping it
> out since it is a little bit ugly&complex.

+1 for keeping it.

>
> [1] https://www.spinics.net/lists/dri-devel/msg172497.html
>
>
>  src/egl/drivers/dri2/platform_android.c | 72 ++++++++++++++++++++++++++++-----
>  1 file changed, 62 insertions(+), 10 deletions(-)
>
> diff --git a/src/egl/drivers/dri2/platform_android.c b/src/egl/drivers/dri2/platform_android.c
> index 7f1a496ea24..0b082fe5dcc 100644
> --- a/src/egl/drivers/dri2/platform_android.c
> +++ b/src/egl/drivers/dri2/platform_android.c
> @@ -27,6 +27,7 @@
>   * DEALINGS IN THE SOFTWARE.
>   */
>
> +#include <cutils/properties.h>
>  #include <errno.h>
>  #include <dlfcn.h>
>  #include <fcntl.h>
> @@ -1117,18 +1118,69 @@ droid_add_configs_for_visuals(_EGLDriver *drv, _EGLDisplay *dpy)
>  static int
>  droid_open_device(struct dri2_egl_display *dri2_dpy)
>  {
> -   int fd = -1, err = -EINVAL;
> -
> -   if (dri2_dpy->gralloc->perform)
> -         err = dri2_dpy->gralloc->perform(dri2_dpy->gralloc,
> -                                          GRALLOC_MODULE_PERFORM_GET_DRM_FD,
> -                                          &fd);
> -   if (err || fd < 0) {
> -      _eglLog(_EGL_WARNING, "fail to get drm fd");
> -      fd = -1;
> +   int prop_set, num_devices, ret;
> +   const int node_type = DRM_NODE_RENDER;
> +   int fd = -1, fallback_fd = -1;
> +
> +   const int MAX_DRM_DEVICES = 32;
> +   char vendor_name[PROPERTY_VALUE_MAX];
> +   prop_set = property_get("drm.gpu.vendor_name", vendor_name, NULL);

Is it really "vendor name" name that we match on? Isn't it a driver
name we want as a vendor could have multiple drivers.

> +   drmVersion ver_filter;
> +   ver_filter.name = vendor_name;
> +
> +   drmDevicePtr devices[MAX_DRM_DEVICES];
> +   num_devices = drmGetDevices2(0, devices, MAX_DRM_DEVICES);
> +   if (num_devices < 0) {
> +      _eglLog(_EGL_WARNING, "Failed to find any DRM devices");
> +      return -1;
> +   }
> +
> +   for (int i = 0; i < num_devices; i++) {
> +      /* Filter out DRM_NODE_ types we aren't interested in */
> +      if (!(devices[i]->available_nodes & (1 << node_type))) {
> +         continue;
> +      }

No braces needed here.

> +
> +      /* Open DRM node FD */
> +      fd = loader_open_device(devices[i]->nodes[node_type]);
> +      if (fd == -1 && errno == EINVAL) {
> +         _eglLog(_EGL_WARNING, "%s()  node #%d failed to open", __func__, i);
> +         continue;
> +      }
> +
> +      /* See if FD matches the driver vendor we want */
> +      if (prop_set && !drmHandleMatch(fd, &ver_filter, NULL)){
> +         _eglLog(_EGL_WARNING, "%s()  node #%d  FD=%d does not match filter", __func__, i , fd);
> +         goto next;
> +      }
> +
> +      /* Successfully found matching FD */
> +      close(fallback_fd);
> +      fallback_fd = -1;
> +      break;
> +
> +next:
> +      if (fallback_fd == -1) {
> +         fallback_fd = fd;
> +         fd = -1;
> +      } else {
> +         close(fd);
> +         fd = -1;
> +      }
> +      continue;
> +   }
> +
> +   if (fallback_fd < 0 && fd < 0) {
> +      _eglLog(_EGL_WARNING, "Failed to open any DRM handle");
> +      return -1;
> +   }
> +
> +   if (fd < 0) {
> +      _eglLog(_EGL_WARNING, "Failed to open desired DRM handle, using fallback");
> +      return fallback_fd;
>     }
>
> -   return (fd >= 0) ? fcntl(fd, F_DUPFD_CLOEXEC, 3) : -1;
> +   return fd;
>  }
>
>  static const struct dri2_egl_display_vtbl droid_display_vtbl = {
> --
> 2.14.1
>
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