Description: Reduce error spew on unsupported or hybrid hardware

Explicitly check if the device is i915 before calling random ioctl()s
to avoid triggering pointless user-visible error messages if it is not.

Origin: upstream b70d65ba25a32a965cc122bf944ba14a1aa0a095
Author: Mark Thompson

--- a/src/intel/intel_driver.c
+++ b/src/intel/intel_driver.c
@@ -312,6 +312,26 @@ return ret;
 }
 #endif
 
+static int
+intel_driver_check_device(int dev_fd)
+{
+  // Ensure that this is actually an i915 DRM device.
+  drmVersion *version;
+  int ret;
+  version = drmGetVersion(dev_fd);
+  if (!version) {
+    fprintf(stderr, "drmGetVersion(%d) failed: %s\n", dev_fd, strerror(errno));
+    close(dev_fd);
+    return 0;
+  }
+  ret = !strcmp(version->name, "i915");
+  drmFreeVersion(version);
+  // Don't print an error here if this device is using a different driver,
+  // because we might be iterating over multiple devices looking for a
+  // compatible one.
+  return ret;
+}
+
 LOCAL int
 intel_driver_init_master(intel_driver_t *driver, const char* dev_name)
 {
@@ -326,6 +346,11 @@ if (dev_fd == -1) {
   return 0;
 }
 
+if (!intel_driver_check_device(dev_fd)) {
+  close(dev_fd);
+  return 0;
+}
+
 // Check that we're authenticated
 memset(&client, 0, sizeof(drm_client_t));
 ret = ioctl(dev_fd, DRM_IOCTL_GET_CLIENT, &client);
@@ -356,6 +381,11 @@ dev_fd = open(dev_name, O_RDWR);
 if (dev_fd == -1)
   return 0;
 
+if (!intel_driver_check_device(dev_fd)) {
+  close(dev_fd);
+  return 0;
+}
+
 ret = intel_driver_init(driver, dev_fd);
 driver->need_close = 1;