Hi Thierry,
Could you explain why in this situation default_fd would be a
non-renderable device node ?
In my understanding, for X11 DRI3 the Xserver is supposed to give you a
renderable device node,
and for Wayland, the device path advertised is the one used by the
server for compositing.
Yours,
Axel Davy
On 23/12/2016 21:36, Thierry Reding wrote:
From: Thierry Reding <tred...@nvidia.com>
If a device doesn't support rendering and support for PRIME isn't
enabled via the DRI_PRIME environment variable or dri.conf, attempt to
find a render node which can be used to offload rendering.
Signed-off-by: Thierry Reding <tred...@nvidia.com>
---
Along with platform and host1x bus support in the loader, this is the
final piece of the puzzle to automatically allow split scanout/render
devices to work with Wayland compositors and the X.Org server.
Note that this requires that the Wayland compositor and X.Org server
are accelerated with a DRI driver to make sure that the default file
descriptor is properly set up.
src/loader/loader.c | 71 ++++++++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 67 insertions(+), 4 deletions(-)
diff --git a/src/loader/loader.c b/src/loader/loader.c
index 505c33133be6..6384432970f2 100644
--- a/src/loader/loader.c
+++ b/src/loader/loader.c
@@ -108,6 +108,71 @@ static char *loader_get_dri_config_device_id(void)
}
#endif
+/*
+ * For all devices that do not support rendering, try to find a different
+ * device that will.
+ *
+ * Note that the absence of a render node doesn't technically imply that
+ * the device can't render, but in practice this should work out fine.
+ */
+static int drm_detect_prime_fd(int default_fd, int *different_device)
+{
+ int err, fd = -ENODEV;
+ drmDevicePtr device;
+
+ err = drmGetDevice(default_fd, &device);
+ if (err < 0)
+ goto err;
+
+ if ((device->available_nodes & (1 << DRM_NODE_RENDER)) == 0) {
+ unsigned int num_devices, i;
+ drmDevicePtr *devices;
+
+ err = drmGetDevices(NULL, 0);
+ if (err < 0)
+ goto err;
+
+ num_devices = err;
+
+ devices = calloc(num_devices, sizeof(drmDevicePtr));
+ if (!devices)
+ goto err;
+
+ err = drmGetDevices(devices, num_devices);
+ if (err < 0) {
+ free(devices);
+ goto err;
+ }
+
+ num_devices = err;
+
+ for (i = 0; i < num_devices; i++) {
+ if (devices[i]->available_nodes & (1 << DRM_NODE_RENDER)) {
+ fd = loader_open_device(devices[i]->nodes[DRM_NODE_RENDER]);
+ if (fd < 0) {
+ fd = -errno;
+ continue;
+ }
+
+ close(default_fd);
+ break;
+ }
+ }
+
+ drmFreeDevices(devices, num_devices);
+ free(devices);
+ }
+
+err:
+ if (fd < 0) {
+ *different_device = 0;
+ return default_fd;
+ }
+
+ *different_device = 1;
+ return fd;
+}
+
static char *drm_construct_id_path_tag(drmDevicePtr device)
{
/* Length of "pci-xxxx_xx_xx_x\0" */
@@ -213,10 +278,8 @@ int loader_get_user_preferred_fd(int default_fd, int
*different_device)
prime = loader_get_dri_config_device_id();
#endif
- if (prime == NULL) {
- *different_device = 0;
- return default_fd;
- }
+ if (prime == NULL || *prime == '\0')
+ return drm_detect_prime_fd(default_fd, different_device);
default_tag = drm_get_id_path_tag_for_fd(default_fd);
if (default_tag == NULL)
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