Re: [PATCH v2] media: iris: add FPS calculation and VPP FW overhead in frequency formula
From: Dikshita Agarwal
Date: Wed Mar 25 2026 - 01:57:56 EST
On 3/20/2026 12:02 PM, Vishnu Reddy wrote:
>
> On 3/13/2026 12:54 PM, Vikash Garodia wrote:
>>
>> On 3/5/2026 7:00 PM, 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@xxxxxxxxxxxxxxxx>
>>> ---
>>> Changes in v2:
>>> - Replaced div_u64 with mult_frac
>>> - Link to v1:
>>> https://lore.kernel.org/r/20260304-update_fps_calculation-v1-1-4eeac373a504@xxxxxxxxxxxxxxxx
>>> ---
>>> drivers/media/platform/qcom/iris/iris_instance.h | 2 ++
>>> drivers/media/platform/qcom/iris/iris_vdec.c | 21
>>> +++++++++++++++++++++
>>> drivers/media/platform/qcom/iris/iris_vpu_common.c | 6 +++++-
>>> 3 files changed, 28 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..180cba36a7f2 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_recv_time_ns;
>>> + u32 frame_count;
>>> 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..88820060e22a 100644
>>> --- a/drivers/media/platform/qcom/iris/iris_vdec.c
>>> +++ b/drivers/media/platform/qcom/iris/iris_vdec.c
>>> @@ -369,6 +369,8 @@ int iris_vdec_streamon_input(struct iris_inst *inst)
>>> if (ret)
>>> return ret;
>>> + inst->frame_count = 0;
>>> +
>>> return iris_process_streamon_input(inst);
>>> }
>>> @@ -411,6 +413,7 @@ 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_recv_time_ns, time_delta_ns;
>>> struct vb2_queue *q;
>>> int ret;
>>> @@ -427,6 +430,24 @@ int iris_vdec_qbuf(struct iris_inst *inst, struct
>>> vb2_v4l2_buffer *vbuf)
>>> return 0;
>>> }
>>> + if (buf->type == BUF_INPUT) {
>>> + cur_buf_recv_time_ns = ktime_get_ns();
>>> +
>>> + if (inst->frame_count == 0) {
>>> + inst->last_buf_recv_time_ns = cur_buf_recv_time_ns;
>>> + inst->frame_rate = MAXIMUM_FPS;
>>> + }
>>> + time_delta_ns = cur_buf_recv_time_ns -
>>> inst->last_buf_recv_time_ns;
>>> +
>>> + if (time_delta_ns >= NSEC_PER_SEC) {
>>> + inst->frame_rate = clamp_t(u32, inst->frame_count,
>>> DEFAULT_FPS,
>>> + MAXIMUM_FPS);
>>> + inst->last_buf_recv_time_ns = cur_buf_recv_time_ns;
>>> + inst->frame_count = 0;
>>> + }
>>> + inst->frame_count++;
>>> + }
>>> +
>>
>> simplifying it ?
>>
>> u64 now_ns, delta_ns;
>>
>> if (buf->type == BUF_INPUT) {
>> now_ns = ktime_get_ns();
>>
>> if (!inst->input_frame_count)
>> inst->buf_fps_start_ts = now_ns;
>
> Here, the actual required FPS will be found after 1 second. until that,
> the initial FPS need to set for max.
why max and not default? setting to max would over vote always in the start
of session.
- Dikshita
>
>>
>> inst->input_frame_count++;
> If we increment the frame_count here, once frame_count becomes zero (after
> 1 sec),
> In next buffer queue, again the above if condition will be true and FPS
> will be set to max.
> I can add the code like below, Let me know your opinion.
>
> if (buf->type == BUF_INPUT) {
> now_ns = ktime_get_ns();
>
> if (!inst->frame_count) {
> inst->last_buf_recv_time_ns = now_ns;
> inst->frame_rate = MAXIMUM_FPS;
> }
> delta_ns = now_ns - inst->buf_fps_start_ts;
>
> if (delta_ns >= NSEC_PER_SEC) {
> inst->frame_rate = clamp_t(u32, inst->frame_count, DEFAULT_FPS,
> MAXIMUM_FPS);
> inst->buf_fps_start_ts = now_ns;
> inst->frame_count = 0;
> }
> inst->frame_count++;
> }
>
> Regards,
> Vishnu Reddy
>
>> delta_ns = now_ns - inst->buf_fps_start_ts;
>> if (delta_ns < NSEC_PER_SEC)
>> //skip the further logic;
>>
>> inst->frame_rate = clamp_t(u32, input_frame_count, DEFAULT_FPS,
>> MAXIMUM_FPS);
>> inst->input_frame_count = 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,
>>