From 54091d0290a8a4c8ae662978e6e9f51c2f515f43 Mon Sep 17 00:00:00 2001
From: Haihao Xiang <haihao.xiang@intel.com>
Date: Tue, 12 Jan 2021 15:33:49 +0800
Subject: [PATCH] msdk: allow user specify a drm device via an env variable

User may specify the required device via GST_MSDK_DRM_DEVICE

Example:
GST_MSDK_DRM_DEVICE=/dev/dri/card0 gst-launch-1.0 videotestsrc ! msdkh264enc
! fakesink

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/-/merge_requests/1953>
---
 sys/msdk/gstmsdkcontext.c | 26 ++++++++++++++++++++++++++
 sys/msdk/meson.build      |  5 +++--
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/sys/msdk/gstmsdkcontext.c b/sys/msdk/gstmsdkcontext.c
index 012efe6..df635c7 100644
--- a/sys/msdk/gstmsdkcontext.c
+++ b/sys/msdk/gstmsdkcontext.c
@@ -34,6 +34,7 @@
 #ifndef _WIN32
 #include <fcntl.h>
 #include <unistd.h>
+#include <xf86drm.h>
 #include <va/va_drm.h>
 #include <gudev/gudev.h>
 #endif
@@ -76,6 +77,31 @@ get_device_id (void)
   const gchar *devnode_path;
   const gchar *devnode_files[2] = { "renderD[0-9]*", "card[0-9]*" };
   int fd = -1, i;
+  const gchar *user_choice = g_getenv ("GST_MSDK_DRM_DEVICE");
+
+  if (user_choice) {
+    if (g_str_has_prefix (user_choice, "/dev/dri/"))
+      fd = open (user_choice, O_RDWR | O_CLOEXEC);
+
+    if (fd >= 0) {
+      drmVersionPtr drm_version = drmGetVersion (fd);
+
+      if (!drm_version || strncmp (drm_version->name, "i915", 4)) {
+        GST_WARNING ("The specified device isn't an Intel device, "
+            "use the default device instead");
+        drmFreeVersion (drm_version);
+        close (fd);
+        fd = -1;
+      } else {
+        GST_DEBUG ("Opened the specified drm device %s", user_choice);
+        drmFreeVersion (drm_version);
+        return fd;
+      }
+    } else {
+      GST_WARNING ("The specified device isn't a valid drm device, "
+          "use the default device instead");
+    }
+  }
 
   client = g_udev_client_new (NULL);
   if (!client)
diff --git a/sys/msdk/meson.build b/sys/msdk/meson.build
index 2c817b6..98570e5 100644
--- a/sys/msdk/meson.build
+++ b/sys/msdk/meson.build
@@ -124,8 +124,9 @@ else
   libva_dep = dependency('libva-drm', required: get_option('msdk'))
   libdl_dep = cc.find_library('dl', required: get_option('msdk'))
   libgudev_dep = dependency('gudev-1.0', required: get_option('msdk'))
-  msdk_deps = declare_dependency(dependencies: [libva_dep, libdl_dep, libgudev_dep])
-  msdk_deps_found = libva_dep.found() and libdl_dep.found() and libgudev_dep.found()
+  libdrm_dep = dependency('libdrm', required: get_option('msdk'))
+  msdk_deps = declare_dependency(dependencies: [libva_dep, libdl_dep, libgudev_dep, libdrm_dep])
+  msdk_deps_found = libva_dep.found() and libdl_dep.found() and libgudev_dep.found() and libdrm_dep.found()
 endif
 
 if msdk_deps_found
-- 
2.7.4