media: iris: disable time-delta-based rate control for VBR

The iris encoder driver was not sending
HFI_PROP_TIME_DELTA_BASED_RATE_CONTROL to the firmware during encoder
initialization. Without this property, the firmware defaults to
time-delta-based rate control (enabled), which calculates the output
bitrate from actual frame timing rather than following the configured
bitrate target.
This caused variable bitrate (VBR) encoding to produce ~5x configured
bitrate. For example, with video_bitrate=896000 (896 Kbps), the output
is ~4.4 Mbps instead of the expected ~896 Kbps.
Time-delta-based rate control is designed for variable frame rate (VFR)
scenarios where the encoder adapts to actual frame timing. However, when
an application explicitly configures a bitrate target, the firmware must
follow that target regardless of frame timing.
Fix this by adding the TIME_DELTA_BASED_RC capability with a default value
of 0 (disabled) and sending HFI_PROP_TIME_DELTA_BASED_RATE_CONTROL = 0 to
the firmware during stream-on, allowing the firmware to use the configured
bitrate as the target.

Signed-off-by: Gourav Kumar <gouravk@qti.qualcomm.com>
Signed-off-by: Vishnu Reddy <busanna.reddy@oss.qualcomm.com>
Reviewed-by: Vikash Garodia <vikash.garodia@oss.qualcomm.com>
Signed-off-by: Bryan O'Donoghue <bod@kernel.org>

5 files changed, 32 insertions, 0 deletions

diff --git a/drivers/media/platform/qcom/iris/iris_ctrls.c b/drivers/media/platform/qcom/iris/iris_ctrls.c
index 2918a7df0b40..bf17d310eac0 100644
--- a/drivers/media/platform/qcom/iris/iris_ctrls.c
+++ b/drivers/media/platform/qcom/iris/iris_ctrls.c
@@ -1499,6 +1499,25 @@ int iris_set_req_sync_frame(struct iris_inst *inst, enum platform_inst_fw_cap_ty
 					     &hfi_val, sizeof(u32));
 }
 
+int iris_set_time_delta_based_rc(struct iris_inst *inst, enum platform_inst_fw_cap_type cap_id)
+{
+	const struct iris_hfi_session_ops *hfi_ops = inst->hfi_session_ops;
+	u32 hfi_id = inst->fw_caps[cap_id].hfi_id;
+	u32 value = inst->fw_caps[cap_id].value;
+
+	/*
+	 * Disable time-delta-based rate control (value = 0).
+	 * This overrides the firmware's default (enabled), ensuring the
+	 * firmware uses the configured bitrate target rather than calculating
+	 * bitrate from frame timing.
+	 */
+	return hfi_ops->session_set_property(inst, hfi_id,
+					     HFI_HOST_FLAGS_NONE,
+					     iris_get_port_info(inst, cap_id),
+					     HFI_PAYLOAD_U32,
+					     &value, sizeof(u32));
+}
+
 int iris_set_properties(struct iris_inst *inst, u32 plane)
 {
 	const struct iris_hfi_session_ops *hfi_ops = inst->hfi_session_ops;
diff --git a/drivers/media/platform/qcom/iris/iris_ctrls.h b/drivers/media/platform/qcom/iris/iris_ctrls.h
index 8d8bbef96007..5180d53d3c90 100644
--- a/drivers/media/platform/qcom/iris/iris_ctrls.h
+++ b/drivers/media/platform/qcom/iris/iris_ctrls.h
@@ -48,6 +48,7 @@ int iris_set_layer_count_gen1(struct iris_inst *inst, enum platform_inst_fw_cap_
 int iris_set_layer_count_gen2(struct iris_inst *inst, enum platform_inst_fw_cap_type cap_id);
 int iris_set_layer_bitrate(struct iris_inst *inst, enum platform_inst_fw_cap_type cap_id);
 int iris_set_req_sync_frame(struct iris_inst *inst, enum platform_inst_fw_cap_type cap_id);
+int iris_set_time_delta_based_rc(struct iris_inst *inst, enum platform_inst_fw_cap_type cap_id);
 int iris_set_properties(struct iris_inst *inst, u32 plane);
 
 #endif
diff --git a/drivers/media/platform/qcom/iris/iris_hfi_gen2.c b/drivers/media/platform/qcom/iris/iris_hfi_gen2.c
index 619a54edb09f..3b8fbefb8b93 100644
--- a/drivers/media/platform/qcom/iris/iris_hfi_gen2.c
+++ b/drivers/media/platform/qcom/iris/iris_hfi_gen2.c
@@ -1241,6 +1241,16 @@ static const struct platform_inst_fw_cap inst_fw_cap_sm8550_enc[] = {
 		.set = iris_set_bitrate_mode_gen2,
 	},
 	{
+		.cap_id = TIME_DELTA_BASED_RC,
+		.min = 0,
+		.max = 1,
+		.step_or_mask = 1,
+		.value = 0,
+		.hfi_id = HFI_PROP_TIME_DELTA_BASED_RATE_CONTROL,
+		.flags = CAP_FLAG_OUTPUT_PORT,
+		.set = iris_set_time_delta_based_rc,
+	},
+	{
 		.cap_id = FRAME_SKIP_MODE,
 		.min = V4L2_MPEG_VIDEO_FRAME_SKIP_MODE_DISABLED,
 		.max = V4L2_MPEG_VIDEO_FRAME_SKIP_MODE_BUF_LIMIT,
diff --git a/drivers/media/platform/qcom/iris/iris_hfi_gen2_defines.h b/drivers/media/platform/qcom/iris/iris_hfi_gen2_defines.h
index a8b47e4ceba0..f43aea10090d 100644
--- a/drivers/media/platform/qcom/iris/iris_hfi_gen2_defines.h
+++ b/drivers/media/platform/qcom/iris/iris_hfi_gen2_defines.h
@@ -67,6 +67,7 @@ enum hfi_rate_control {
 };
 
 #define HFI_PROP_RATE_CONTROL			0x0300012a
+#define HFI_PROP_TIME_DELTA_BASED_RATE_CONTROL	0x0300012b
 #define HFI_PROP_QP_PACKED			0x0300012e
 #define HFI_PROP_MIN_QP_PACKED			0x0300012f
 #define HFI_PROP_MAX_QP_PACKED			0x03000130
diff --git a/drivers/media/platform/qcom/iris/iris_platform_common.h b/drivers/media/platform/qcom/iris/iris_platform_common.h
index d8481a9689d5..974809509146 100644
--- a/drivers/media/platform/qcom/iris/iris_platform_common.h
+++ b/drivers/media/platform/qcom/iris/iris_platform_common.h
@@ -185,6 +185,7 @@ enum platform_inst_fw_cap_type {
 	LAYER4_BITRATE_HEVC,
 	LAYER5_BITRATE_HEVC,
 	REQUEST_SYNC_FRAME,
+	TIME_DELTA_BASED_RC,
 	INST_FW_CAP_MAX,
 };