From a2b219c7e1400146b2dcad77f41fe79d35c275cb Mon Sep 17 00:00:00 2001
From: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Date: Mon, 20 Jun 2022 12:22:20 -0400
Subject: [PATCH] v4l2codecs: hevc: Add an API check

This adds an API check and bump recommended base kernel version to 5.20.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/1079>
---
 .../sys/v4l2codecs/gstv4l2codech265dec.c      | 67 ++++++++++++++++++-
 1 file changed, 66 insertions(+), 1 deletion(-)

diff --git a/subprojects/gst-plugins-bad/sys/v4l2codecs/gstv4l2codech265dec.c b/subprojects/gst-plugins-bad/sys/v4l2codecs/gstv4l2codech265dec.c
index 459437209e..45c3e72cdd 100644
--- a/subprojects/gst-plugins-bad/sys/v4l2codecs/gstv4l2codech265dec.c
+++ b/subprojects/gst-plugins-bad/sys/v4l2codecs/gstv4l2codech265dec.c
@@ -31,7 +31,7 @@
 #define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c))
 
 #define V4L2_MIN_KERNEL_VER_MAJOR 5
-#define V4L2_MIN_KERNEL_VER_MINOR 18
+#define V4L2_MIN_KERNEL_VER_MINOR 20
 #define V4L2_MIN_KERNEL_VERSION KERNEL_VERSION(V4L2_MIN_KERNEL_VER_MAJOR, V4L2_MIN_KERNEL_VER_MINOR, 0)
 
 GST_DEBUG_CATEGORY_STATIC (v4l2_h265dec_debug);
@@ -136,6 +136,66 @@ needs_start_codes (GstV4l2CodecH265Dec * self)
   return self->start_code == V4L2_STATELESS_HEVC_START_CODE_ANNEX_B;
 }
 
+static gboolean
+gst_v4l2_decoder_h265_api_check (GstV4l2Decoder * decoder)
+{
+  guint i, ret_size;
+  /* *INDENT-OFF* */
+  #define SET_ID(cid) .id = (cid), .name = #cid
+  struct
+  {
+    const gchar *name;
+    unsigned int id;
+    unsigned int size;
+    gboolean optional;
+  } controls[] = {
+    {
+      SET_ID (V4L2_CID_STATELESS_HEVC_SPS),
+      .size = sizeof(struct v4l2_ctrl_hevc_sps),
+    }, {
+      SET_ID (V4L2_CID_STATELESS_HEVC_PPS),
+      .size = sizeof(struct v4l2_ctrl_hevc_pps),
+    }, {
+      SET_ID (V4L2_CID_STATELESS_HEVC_SCALING_MATRIX),
+      .size = sizeof(struct v4l2_ctrl_hevc_scaling_matrix),
+      .optional = TRUE,
+    }, {
+      SET_ID (V4L2_CID_STATELESS_HEVC_DECODE_PARAMS),
+      .size = sizeof(struct v4l2_ctrl_hevc_decode_params),
+    }, {
+      SET_ID (V4L2_CID_STATELESS_HEVC_SLICE_PARAMS),
+      .size = sizeof(struct v4l2_ctrl_hevc_slice_params),
+      .optional = TRUE,
+    }
+  };
+  #undef SET_ID
+  /* *INDENT-ON* */
+
+  /*
+   * Compatibility check: make sure the pointer controls are
+   * the right size.
+   */
+  for (i = 0; i < G_N_ELEMENTS (controls); i++) {
+    gboolean control_found;
+
+    control_found = gst_v4l2_decoder_query_control_size (decoder,
+        controls[i].id, &ret_size);
+
+    if (!controls[i].optional && !control_found) {
+      GST_WARNING ("Driver is missing %s support.", controls[i].name);
+      return FALSE;
+    }
+
+    if (control_found && ret_size != controls[i].size) {
+      GST_WARNING ("%s control size mismatch: got %d bytes but %d expected.",
+          controls[i].name, ret_size, controls[i].size);
+      return FALSE;
+    }
+  }
+
+  return TRUE;
+}
+
 
 static gboolean
 gst_v4l2_codec_h265_dec_open (GstVideoDecoder * decoder)
@@ -1611,6 +1671,11 @@ gst_v4l2_codec_h265_dec_register (GstPlugin * plugin, GstV4l2Decoder * decoder,
         (version >> 16) & 0xff, (version >> 8) & 0xff,
         V4L2_MIN_KERNEL_VER_MAJOR, V4L2_MIN_KERNEL_VER_MINOR);
 
+  if (!gst_v4l2_decoder_h265_api_check (decoder)) {
+    GST_WARNING ("Not registering H265 decoder as it failed ABI check.");
+    goto done;
+  }
+
   gst_v4l2_decoder_register (plugin, GST_TYPE_V4L2_CODEC_H265_DEC,
       (GClassInitFunc) gst_v4l2_codec_h265_dec_subclass_init,
       gst_mini_object_ref (GST_MINI_OBJECT (device)),