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

[Vishnu Reddy <busanna.reddy@oss.qualcomm.com>]

On 3/31/2026 7:45 PM, Bryan O'Donoghue wrote:
> 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'
>
Ack
Vishnu Reddy.
> ---
> bod