[PATCH v2] media: iris: optimize COMV buffer allocation for VPU3x and VPU4x

[PATCH v2] media: iris: optimize COMV buffer allocation for VPU3x and VPU4x

[Vishnu Reddy]

The existing iris_vpu_dec_comv_size() used VIDEO_MAX_FRAME (32) as
num_comv count unconditionally when calculating the co-located motion
vector (COMV) buffer size. This resulted in an oversized COMV buffer
allocation throughout decode session, wasting memory regardless of
actual number of buffers required.

For VPU3x and VPU4x platforms, introduce iris_vpu3x_4x_dec_comv_size() to
replace iris_vpu_dec_comv_size(). These derive num_comv dynamically, it
uses inst->fw_min_count once the firmware has reported its buffer
requirements, and fallback to output count during initialization before
firmware has communicated its requirements. This aligns the COMV buffer
size to the actual count needed rather than always allocating with fixed
VIDEO_MAX_FRAME value.

Additionally, during iris_vdec_inst_init(), fw_min_count was initialized
to MIN_BUFFERS instead of 0. This masked the fallback logic and caused the
COMV size calculation to use MIN_BUFFERS even before firmware had reported
its actual requirements. Fix this by initializing fw_min_count to 0.

During testing of 1080p AVC, it reduces the COMV buffer size from 32.89MB
to 6.16MB per decode session, significantly reducing memory consumption.

Signed-off-by: Vishnu Reddy <busanna.reddy@oss.qualcomm.com>
---
Changes in v2:
- Update commit description (Bryan)
- Update hfi comv buffer count value to use actual num_comv count which
  used for buffer calculation to avoid any overhead or fixed values (Vikash)
- Link to v1: https://lore.kernel.org/r/20260421-optimize_comv_buffer-v1-1-7c9a24da3ad3@oss.qualcomm.com
---
 .../platform/qcom/iris/iris_hfi_gen2_command.c     |  9 +-------
 drivers/media/platform/qcom/iris/iris_vdec.c       |  2 +-
 drivers/media/platform/qcom/iris/iris_vpu_buffer.c | 26 ++++++++++++++++++++--
 3 files changed, 26 insertions(+), 11 deletions(-)

diff --git a/drivers/media/platform/qcom/iris/iris_hfi_gen2_command.c b/drivers/media/platform/qcom/iris/iris_hfi_gen2_command.c
index 30bfd90d423b..3ade359f21e5 100644
--- a/drivers/media/platform/qcom/iris/iris_hfi_gen2_command.c
+++ b/drivers/media/platform/qcom/iris/iris_hfi_gen2_command.c
@@ -10,7 +10,6 @@
 
 #define UNSPECIFIED_COLOR_FORMAT 5
 #define NUM_SYS_INIT_PACKETS 8
-#define NUM_COMV_AV1 18
 
 #define SYS_INIT_PKT_SIZE (sizeof(struct iris_hfi_header) + \
 	NUM_SYS_INIT_PACKETS * (sizeof(struct iris_hfi_packet) + sizeof(u32)))
@@ -1212,13 +1211,7 @@ static int iris_set_num_comv(struct iris_inst *inst)
 	u32 num_comv;
 
 	caps = core->iris_platform_data->inst_caps;
-
-	/*
-	 * AV1 needs more comv buffers than other codecs.
-	 * Update accordingly.
-	 */
-	num_comv = (inst->codec == V4L2_PIX_FMT_AV1) ?
-				NUM_COMV_AV1 : caps->num_comv;
+	num_comv = caps->num_comv;
 
 	return core->hfi_ops->session_set_property(inst,
 						   HFI_PROP_COMV_BUFFER_COUNT,
diff --git a/drivers/media/platform/qcom/iris/iris_vdec.c b/drivers/media/platform/qcom/iris/iris_vdec.c
index 719217399a30..f433065e08b2 100644
--- a/drivers/media/platform/qcom/iris/iris_vdec.c
+++ b/drivers/media/platform/qcom/iris/iris_vdec.c
@@ -24,7 +24,7 @@ int iris_vdec_inst_init(struct iris_inst *inst)
 	inst->fmt_src = kzalloc_obj(*inst->fmt_src);
 	inst->fmt_dst = kzalloc_obj(*inst->fmt_dst);
 
-	inst->fw_min_count = MIN_BUFFERS;
+	inst->fw_min_count = 0;
 
 	f = inst->fmt_src;
 	f->type = V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE;
diff --git a/drivers/media/platform/qcom/iris/iris_vpu_buffer.c b/drivers/media/platform/qcom/iris/iris_vpu_buffer.c
index 9270422c1601..924b210cc4cd 100644
--- a/drivers/media/platform/qcom/iris/iris_vpu_buffer.c
+++ b/drivers/media/platform/qcom/iris/iris_vpu_buffer.c
@@ -731,6 +731,28 @@ static u32 iris_vpu_dec_comv_size(struct iris_inst *inst)
 	u32 height = f->fmt.pix_mp.height;
 	u32 width = f->fmt.pix_mp.width;
 
+	if (inst->codec == V4L2_PIX_FMT_H264)
+		return hfi_buffer_comv_h264d(width, height, num_comv);
+	else if (inst->codec == V4L2_PIX_FMT_HEVC)
+		return hfi_buffer_comv_h265d(width, height, num_comv);
+
+	return 0;
+}
+
+static u32 iris_vpu3x_4x_dec_comv_size(struct iris_inst *inst)
+{
+	u32 num_comv = iris_vpu_buf_count(inst, BUF_OUTPUT);
+	struct v4l2_format *f = inst->fmt_src;
+	u32 height = f->fmt.pix_mp.height;
+	u32 width = f->fmt.pix_mp.width;
+	struct platform_inst_caps *caps;
+
+	if (inst->fw_min_count)
+		num_comv = inst->fw_min_count;
+
+	caps = inst->core->iris_platform_data->inst_caps;
+	caps->num_comv = num_comv;
+
 	if (inst->codec == V4L2_PIX_FMT_H264)
 		return hfi_buffer_comv_h264d(width, height, num_comv);
 	else if (inst->codec == V4L2_PIX_FMT_HEVC)
@@ -2025,7 +2047,7 @@ u32 iris_vpu_buf_size(struct iris_inst *inst, enum iris_buffer_type buffer_type)
 
 	static const struct iris_vpu_buf_type_handle dec_internal_buf_type_handle[] = {
 		{BUF_BIN,         iris_vpu_dec_bin_size             },
-		{BUF_COMV,        iris_vpu_dec_comv_size            },
+		{BUF_COMV,        iris_vpu3x_4x_dec_comv_size       },
 		{BUF_NON_COMV,    iris_vpu_dec_non_comv_size        },
 		{BUF_LINE,        iris_vpu_dec_line_size            },
 		{BUF_PERSIST,     iris_vpu_dec_persist_size         },
@@ -2098,7 +2120,7 @@ u32 iris_vpu4x_buf_size(struct iris_inst *inst, enum iris_buffer_type buffer_typ
 
 	static const struct iris_vpu_buf_type_handle dec_internal_buf_type_handle[] = {
 		{BUF_BIN,         iris_vpu_dec_bin_size         },
-		{BUF_COMV,        iris_vpu_dec_comv_size        },
+		{BUF_COMV,        iris_vpu3x_4x_dec_comv_size   },
 		{BUF_NON_COMV,    iris_vpu_dec_non_comv_size    },
 		{BUF_LINE,        iris_vpu4x_dec_line_size      },
 		{BUF_PERSIST,     iris_vpu4x_dec_persist_size   },

---
base-commit: 254f49634ee16a731174d2ae34bc50bd5f45e731
change-id: 20260421-optimize_comv_buffer-ae7107673609

Best regards,
-- 
Vishnu Reddy <busanna.reddy@oss.qualcomm.com>