Re: [PATCH v4] media: iris: add FPS calculation and VPP FW overhead in frequency formula

[Bryan O'Donoghue <bod@kernel.org>]

On 25/03/2026 16:35, Vishnu Reddy wrote:
> The driver was using a fixed default FPS value when calculating the VPU
> frequency. This caused wrong frequency requests for high‑frame‑rate
> streams, for example 4K at 240 FPS. Because of this, the hardware was
> running at a lower frequency than needed.
> 
> Add the FPS measurement based on the decoder input buffer arrival rate.
> The measured FPS is stored per instance and used in frequency calculation
> instead of the fixed default FPS. The value is clamped so that it does
> not exceed platform limits. Add a VPP firmware overhead when running in
> STAGE_2.
> 
> Signed-off-by: Vishnu Reddy <busanna.reddy@oss.qualcomm.com>
> ---
> Changes in v4:
> - Renamed the variable names (Vikash Garodia)
> - Updated the fps calculation logic (Vikash Garodia)
> - Link to v3: https://lore.kernel.org/r/20260325-update_fps_calculation-v3-1-b2ec654f7e4d@oss.qualcomm.com
> 
> Changes in v3:
> - Updated the frame_count condition check (Vikash Garodia)
> - Link to v2: https://lore.kernel.org/r/20260305-update_fps_calculation-v2-1-e3b5cccb1246@oss.qualcomm.com
> 
> Changes in v2:
> - Replaced div_u64 with mult_frac (Konrad Dybcio)
> - Link to v1: https://lore.kernel.org/r/20260304-update_fps_calculation-v1-1-4eeac373a504@oss.qualcomm.com
> ---
>   drivers/media/platform/qcom/iris/iris_instance.h   |  2 ++
>   drivers/media/platform/qcom/iris/iris_vdec.c       | 20 ++++++++++++++++++++
>   drivers/media/platform/qcom/iris/iris_vpu_common.c |  6 +++++-
>   3 files changed, 27 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/platform/qcom/iris/iris_instance.h b/drivers/media/platform/qcom/iris/iris_instance.h
> index 16965150f427..a47cd949645f 100644
> --- a/drivers/media/platform/qcom/iris/iris_instance.h
> +++ b/drivers/media/platform/qcom/iris/iris_instance.h
> @@ -109,6 +109,8 @@ struct iris_inst {
>   	u32				metadata_idx;
>   	u32				codec;
>   	bool				last_buffer_dequeued;
> +	u64				last_buf_ns;
> +	u32				frame_counter;
>   	u32				frame_rate;
>   	u32				operating_rate;
>   	u32				hfi_rc_type;
> diff --git a/drivers/media/platform/qcom/iris/iris_vdec.c b/drivers/media/platform/qcom/iris/iris_vdec.c
> index 719217399a30..7fb45df37db6 100644
> --- a/drivers/media/platform/qcom/iris/iris_vdec.c
> +++ b/drivers/media/platform/qcom/iris/iris_vdec.c
> @@ -54,6 +54,7 @@ int iris_vdec_inst_init(struct iris_inst *inst)
>   	f->fmt.pix_mp.quantization = V4L2_QUANTIZATION_DEFAULT;
>   	inst->buffers[BUF_OUTPUT].min_count = iris_vpu_buf_count(inst, BUF_OUTPUT);
>   	inst->buffers[BUF_OUTPUT].size = f->fmt.pix_mp.plane_fmt[0].sizeimage;
> +	inst->frame_rate = MAXIMUM_FPS;
> 
>   	memcpy(&inst->fw_caps[0], &core->inst_fw_caps_dec[0],
>   	       INST_FW_CAP_MAX * sizeof(struct platform_inst_fw_cap));
> @@ -369,6 +370,8 @@ int iris_vdec_streamon_input(struct iris_inst *inst)
>   	if (ret)
>   		return ret;
> 
> +	inst->frame_counter = 0;
> +
>   	return iris_process_streamon_input(inst);
>   }
> 
> @@ -411,6 +414,7 @@ int iris_vdec_qbuf(struct iris_inst *inst, struct vb2_v4l2_buffer *vbuf)
>   {
>   	struct iris_buffer *buf = to_iris_buffer(vbuf);
>   	struct vb2_buffer *vb2 = &vbuf->vb2_buf;
> +	u64 cur_buf_ns, delta_ns;
>   	struct vb2_queue *q;
>   	int ret;
> 
> @@ -427,6 +431,22 @@ int iris_vdec_qbuf(struct iris_inst *inst, struct vb2_v4l2_buffer *vbuf)
>   		return 0;
>   	}
> 
> +	if (buf->type == BUF_INPUT) {
> +		cur_buf_ns = ktime_get_ns();
> +
> +		if (!inst->frame_counter)
> +			inst->last_buf_ns = cur_buf_ns;
> +
> +		inst->frame_counter++;
> +		delta_ns = cur_buf_ns - inst->last_buf_ns;
> +
> +		if (delta_ns >= NSEC_PER_SEC) {
> +			inst->frame_rate = clamp_t(u32, inst->frame_counter, DEFAULT_FPS,
> +						   MAXIMUM_FPS);
> +			inst->frame_counter = 0;
> +		}
> +	}
> +
>   	iris_scale_power(inst);
> 
>   	return iris_queue_buffer(inst, buf);
> diff --git a/drivers/media/platform/qcom/iris/iris_vpu_common.c b/drivers/media/platform/qcom/iris/iris_vpu_common.c
> index 548e5f1727fd..d621ccffa868 100644
> --- a/drivers/media/platform/qcom/iris/iris_vpu_common.c
> +++ b/drivers/media/platform/qcom/iris/iris_vpu_common.c
> @@ -416,7 +416,7 @@ u64 iris_vpu3x_vpu4x_calculate_frequency(struct iris_inst *inst, size_t data_siz
>   	u32 height, width, mbs_per_second, mbpf;
>   	u64 fw_cycles, fw_vpp_cycles;
>   	u64 vsp_cycles, vpp_cycles;
> -	u32 fps = DEFAULT_FPS;
> +	u32 fps = inst->frame_rate;
> 
>   	width = max(inp_f->fmt.pix_mp.width, inst->crop.width);
>   	height = max(inp_f->fmt.pix_mp.height, inst->crop.height);
> @@ -435,6 +435,10 @@ u64 iris_vpu3x_vpu4x_calculate_frequency(struct iris_inst *inst, size_t data_siz
>   	if (inst->fw_caps[PIPE].value > 1)
>   		vpp_cycles += div_u64(vpp_cycles * 59, 1000);
> 
> +	/* 1.05 is VPP FW overhead */
> +	if (inst->fw_caps[STAGE].value == STAGE_2)
> +		vpp_cycles += mult_frac(vpp_cycles, 5, 100);
> +
>   	vsp_cycles = fps * data_size * 8;
>   	vsp_cycles = div_u64(vsp_cycles, 2);
>   	/* VSP FW overhead 1.05 */
> 
> ---
> base-commit: f505e978d1a0442adbbde48aed38c084ddea6d6e
> change-id: 20260304-update_fps_calculation-98ee7f7507b1
> 
> Best regards,
> --
> Vishnu Reddy <busanna.reddy@oss.qualcomm.com>
> 
> 

Please fix your doxygen.

[[ATTACHMENT|junit/test-kernel-doc.log.txt]]
4 warnings as errors
Warning: drivers/media/platform/qcom/iris/iris_instance.h:124 struct 
member 'last_buf_ns' not described in 'iris_inst'
Warning: drivers/media/platform/qcom/iris/iris_instance.h:124 struct 
member 'frame_counter' not described in 'iris_inst'
Warning: drivers/media/platform/qcom/iris/iris_instance.h:124 struct 
member 'last_buf_ns' not described in 'iris_inst'
Warning: drivers/media/platform/qcom/iris/iris_instance.h:124 struct 
member 'frame_counter' not described in 'iris_inst'


System Err:

[[ATTACHMENT|junit/test-kernel-doc.err.txt]]
Warning: drivers/media/platform/qcom/iris/iris_instance.h:124 struct 
member 'last_buf_ns' not described in 'iris_inst'
Warning: drivers/media/platform/qcom/iris/iris_instance.h:124 struct 
member 'frame_counter' not described in 'iris_inst'
Warning: drivers/media/platform/qcom/iris/iris_instance.h:124 struct 
member 'last_buf_ns' not described in 'iris_inst'
Warning: drivers/media/platform/qcom/iris/iris_instance.h:124 struct 
member 'frame_counter' not described in 'iris_inst'

---
bod