ampere-av1 Phase 2 step 1: third-device fd scaffolding for vpu981

RK3588 has THREE hantro-vpu instances (legacy MPEG2/VP8 at /dev/video2,
encoder at /dev/video3, vpu981 AV1 at /dev/video4). The existing
2-device probe is "RK3399-shaped knowledge" — silently picks the first
hantro-vpu and never finds vpu981.

This commit adds:
- video_fd_vpu981 + media_fd_vpu981 slots to request_data
- video_node_supports_output_fmt(): capability probe via VIDIOC_ENUM_FMT
  on OUTPUT/OUTPUT_MPLANE queues
- find_decoder_device_by_driver_with_fmt(): walks /dev/media* matching
  driver name AND capability filter (V4L2_PIX_FMT_AV1_FRAME for vpu981)
- 'a' kind in request_device_kind_for_profile (VAProfileAV1Profile0)
- 'a' branch in request_switch_device_for_profile
- vpu981 probe at backend init, alongside existing rkvdec + hantro
- vpu981 fd cleanup in RequestTerminate
- VAProfileAV1Profile0 → V4L2_PIX_FMT_AV1_FRAME in codec.c

Verified on ampere:

  $ LIBVA_DRIVER_NAME=v4l2_request ffmpeg ... 2>&1 | grep iter38
  v4l2-request: auto-selected codec device: /dev/video1 + /dev/media0
  v4l2-request: iter38: also opened hantro-vpu decoder at /dev/video2 + /dev/media1
  v4l2-request: ampere-av1: vpu981 AV1 decoder at /dev/video4 + /dev/media3

Three devices opened. HEVC still works (iter2 EXT_SPS_RPS probe still
triggers on rkvdec, sibling-campaign bit-perfect behaviour preserved).

Next steps: config.c advertise VAProfileAV1Profile0, surface.h add
av1 substruct, picture.c dispatch, av1.{c,h} for the codec dispatch
(~700 LoC mirroring Kwiboo v4l2_request_av1.c).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/codec.c

@@ -44,6 +44,8 @@ unsigned int pixelformat_for_profile(VAProfile profile)
 		return V4L2_PIX_FMT_VP8_FRAME;
 	case VAProfileVP9Profile0:
 		return V4L2_PIX_FMT_VP9_FRAME;
+	case VAProfileAV1Profile0:
+		return V4L2_PIX_FMT_AV1_FRAME;
 	default:
 		return 0;
 	}

src/request.c

@@ -325,6 +325,37 @@ static bool probe_hevc_ext_sps_rps_controls(int video_fd)
 	return true;
 }
 
+/*
+ * Inspect a /dev/videoN's OUTPUT formats for `want_pixfmt`. Returns true
+ * iff at least one OUTPUT/OUTPUT_MPLANE format matches.
+ *
+ * Used to discriminate between multiple devices sharing a driver name —
+ * RK3588 has 3 hantro-vpu instances and only one of them is vpu981 (the
+ * dedicated AV1 decoder advertising V4L2_PIX_FMT_AV1_FRAME).
+ */
+static bool video_node_supports_output_fmt(int video_fd, uint32_t want_pixfmt)
+{
+	struct v4l2_fmtdesc desc;
+	const enum v4l2_buf_type types[] = {
+		V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE,
+		V4L2_BUF_TYPE_VIDEO_OUTPUT,
+	};
+	unsigned int t, i;
+
+	for (t = 0; t < sizeof(types) / sizeof(types[0]); t++) {
+		for (i = 0; i < 64; i++) {
+			memset(&desc, 0, sizeof desc);
+			desc.index = i;
+			desc.type = types[t];
+			if (ioctl(video_fd, VIDIOC_ENUM_FMT, &desc) < 0)
+				break;
+			if (desc.pixelformat == want_pixfmt)
+				return true;
+		}
+	}
+	return false;
+}
+
 static int find_decoder_device_by_driver(const char *want_driver,
 					 char *video_out, size_t video_out_sz,
 					 char *media_out, size_t media_out_sz)
@@ -372,6 +403,65 @@ static int find_decoder_device_by_driver(const char *want_driver,
 	return -1;
 }
 
+/*
+ * ampere-av1-enablement Phase 2 — like find_decoder_device_by_driver but
+ * additionally verifies the resolved /dev/videoN advertises `want_pixfmt`
+ * as an OUTPUT format. Required for RK3588 where 3 hantro-vpu instances
+ * share the driver name but only one is vpu981 (AV1 decoder).
+ *
+ * Walks all /dev/media* with matching driver name; takes the first hit
+ * whose OUTPUT formats include `want_pixfmt`. Non-matching candidates
+ * (encoder-only nodes, legacy hantro for MPEG2/VP8) are skipped.
+ */
+static int find_decoder_device_by_driver_with_fmt(const char *want_driver,
+						  uint32_t want_pixfmt,
+						  char *video_out,
+						  size_t video_out_sz,
+						  char *media_out,
+						  size_t media_out_sz)
+{
+	struct media_device_info info;
+	char path[32];
+	char vpath[32];
+	int fd, vfd, i;
+
+	for (i = 0; i < 16; i++) {
+		snprintf(path, sizeof path, "/dev/media%d", i);
+		fd = open(path, O_RDWR | O_NONBLOCK);
+		if (fd < 0)
+			continue;
+		memset(&info, 0, sizeof info);
+		if (ioctl(fd, MEDIA_IOC_DEVICE_INFO, &info) != 0) {
+			close(fd);
+			continue;
+		}
+		if (strcmp(info.driver, want_driver) != 0) {
+			close(fd);
+			continue;
+		}
+		if (find_decoder_video_node_via_topology(fd, vpath,
+							 sizeof vpath) != 0) {
+			close(fd);
+			continue;
+		}
+		close(fd);
+
+		/* Capability check: does this /dev/videoN advertise the
+		 * codec-specific OUTPUT format? */
+		vfd = open(vpath, O_RDWR | O_NONBLOCK);
+		if (vfd < 0)
+			continue;
+		if (video_node_supports_output_fmt(vfd, want_pixfmt)) {
+			close(vfd);
+			snprintf(video_out, video_out_sz, "%s", vpath);
+			snprintf(media_out, media_out_sz, "%s", path);
+			return 0;
+		}
+		close(vfd);
+	}
+	return -1;
+}
+
 static int find_codec_device(char *video_out, size_t video_out_sz,
 			     char *media_out, size_t media_out_sz)
 {
@@ -408,6 +498,8 @@ char request_device_kind_for_profile(VAProfile profile)
 	case VAProfileMPEG2Main:
 	case VAProfileVP8Version0_3:
 		return 'h';
+	case VAProfileAV1Profile0:
+		return 'a';   /* ampere-av1-enablement: vpu981 dedicated AV1 */
 	default:
 		return '?';
 	}
@@ -437,6 +529,9 @@ int request_switch_device_for_profile(struct request_data *driver_data,
 	} else if (kind == 'h') {
 		target_video = driver_data->video_fd_hantro;
 		target_media = driver_data->media_fd_hantro;
+	} else if (kind == 'a') {
+		target_video = driver_data->video_fd_vpu981;
+		target_media = driver_data->media_fd_vpu981;
 	} else {
 		return -1;
 	}
@@ -624,6 +719,8 @@ VAStatus VA_DRIVER_INIT_FUNC(VADriverContextP context)
 	driver_data->media_fd_rkvdec = -1;
 	driver_data->video_fd_hantro = -1;
 	driver_data->media_fd_hantro = -1;
+	driver_data->video_fd_vpu981 = -1;
+	driver_data->media_fd_vpu981 = -1;
 
 	/*
 	 * iter38: probe BOTH rkvdec and hantro-vpu so a single libva session
@@ -681,6 +778,40 @@ VAStatus VA_DRIVER_INIT_FUNC(VADriverContextP context)
 			}
 		}
 		(void)primary_driver;
+
+		/*
+		 * ampere-av1-enablement Phase 2 — additionally probe for
+		 * vpu981 (RK3588's dedicated AV1 decoder). Driver name
+		 * "hantro-vpu" alone is ambiguous on RK3588 (3 instances:
+		 * legacy MPEG2/VP8, encoder, vpu981 AV1). Discriminate by
+		 * V4L2_PIX_FMT_AV1_FRAME capability. If the primary or alt
+		 * hantro happens to BE vpu981 (unlikely but possible on
+		 * non-RK3588 boards), this probe finds it again and we just
+		 * dedupe via the fd value.
+		 */
+		{
+			static char av1_video[32], av1_media[32];
+			if (find_decoder_device_by_driver_with_fmt(
+				    "hantro-vpu", V4L2_PIX_FMT_AV1_FRAME,
+				    av1_video, sizeof av1_video,
+				    av1_media, sizeof av1_media) == 0) {
+				int av1_v = open(av1_video, O_RDWR | O_NONBLOCK);
+				int av1_m = (av1_v >= 0)
+					? open(av1_media, O_RDWR | O_NONBLOCK)
+					: -1;
+				if (av1_v >= 0 && av1_m >= 0) {
+					driver_data->video_fd_vpu981 = av1_v;
+					driver_data->media_fd_vpu981 = av1_m;
+					request_log(
+					    "ampere-av1: vpu981 AV1 decoder "
+					    "at %s + %s\n",
+					    av1_video, av1_media);
+				} else {
+					if (av1_v >= 0) close(av1_v);
+					if (av1_m >= 0) close(av1_m);
+				}
+			}
+		}
 	}
 
 	/*
@@ -745,9 +876,15 @@ VAStatus RequestTerminate(VADriverContextP context)
 		close(driver_data->video_fd_hantro);
 	if (driver_data->media_fd_hantro >= 0)
 		close(driver_data->media_fd_hantro);
+	if (driver_data->video_fd_vpu981 >= 0)
+		close(driver_data->video_fd_vpu981);
+	if (driver_data->media_fd_vpu981 >= 0)
+		close(driver_data->media_fd_vpu981);
 	/* Fall back to direct close if neither alt fd captured the active
 	 * pair (env-override path). */
-	if (driver_data->video_fd_rkvdec < 0 && driver_data->video_fd_hantro < 0) {
+	if (driver_data->video_fd_rkvdec < 0 &&
+	    driver_data->video_fd_hantro < 0 &&
+	    driver_data->video_fd_vpu981 < 0) {
 		if (driver_data->video_fd >= 0)
 			close(driver_data->video_fd);
 		if (driver_data->media_fd >= 0)

src/request.h

@@ -79,6 +79,20 @@ struct request_data {
 	int video_fd_hantro;
 	int media_fd_hantro;
 
+	/*
+	 * ampere-av1-enablement Phase 2 — vpu981 is a THIRD physical
+	 * hantro-vpu instance on RK3588 (separate from the legacy MPEG2/VP8
+	 * hantro at /dev/video2). It's the dedicated AV1 decoder at
+	 * /dev/video4 with card name "rockchip,rk3588-av1-vpu-dec".
+	 *
+	 * Driver-name alone ("hantro-vpu") is ambiguous on RK3588 — three
+	 * instances share the name. The probe discriminates by capability:
+	 * which OUTPUT format does the device advertise? Only vpu981
+	 * exposes V4L2_PIX_FMT_AV1_FRAME.
+	 */
+	int video_fd_vpu981;
+	int media_fd_vpu981;
+
 	/*
 	 * iter2 (ampere-kernel-decoders campaign) — per-fd probe result
 	 * for the V4L2_CID_STATELESS_HEVC_EXT_SPS_{ST,LT}_RPS controls