Re: [PATCH 2/4] media: qcom: iris: Add Long-Term Reference support for encoder

[Dikshita Agarwal <dikshita.agarwal@oss.qualcomm.com>]

On 11/27/2025 1:14 PM, Wangao Wang wrote:
> Add Long-Term Reference(LTR) frame support for both gen1 and gen2
> encoders by enabling the following V4L2 controls:
> V4L2_CID_MPEG_VIDEO_LTR_COUNT
> V4L2_CID_MPEG_VIDEO_USE_LTR_FRAMES
> V4L2_CID_MPEG_VIDEO_FRAME_LTR_INDEX
> 
> Key changes:
> Added LTR capability IDs and V4L2 controls.
> Implemented handlers for LTR count, use, and mark (gen1/gen2).
> Defined new HFI properties and structures for LTR.
> Updated platform capability tables and buffer size calculations.
> 
> Signed-off-by: Wangao Wang <wangao.wang@oss.qualcomm.com>
> ---
>  drivers/media/platform/qcom/iris/iris_ctrls.c      | 126 +++++++++++++++++++++
>  drivers/media/platform/qcom/iris/iris_ctrls.h      |   5 +
>  .../platform/qcom/iris/iris_hfi_gen1_command.c     |  25 ++++
>  .../platform/qcom/iris/iris_hfi_gen1_defines.h     |  24 ++++
>  .../platform/qcom/iris/iris_hfi_gen2_defines.h     |   3 +
>  .../platform/qcom/iris/iris_platform_common.h      |   6 +
>  .../media/platform/qcom/iris/iris_platform_gen1.c  |  30 +++++
>  .../media/platform/qcom/iris/iris_platform_gen2.c  |  30 +++++
>  drivers/media/platform/qcom/iris/iris_vpu_buffer.c |  33 ++++--
>  9 files changed, 270 insertions(+), 12 deletions(-)
> 

>  static struct platform_inst_caps platform_inst_cap_sm8550 = {
> diff --git a/drivers/media/platform/qcom/iris/iris_vpu_buffer.c b/drivers/media/platform/qcom/iris/iris_vpu_buffer.c
> index 1e54ace966c74956208d88f06837b97b1fd48e17..8139fefe40fe179ff7862bbca879ce94c71c1f89 100644
> --- a/drivers/media/platform/qcom/iris/iris_vpu_buffer.c
> +++ b/drivers/media/platform/qcom/iris/iris_vpu_buffer.c
> @@ -668,6 +668,19 @@ static u32 iris_vpu_enc_bin_size(struct iris_inst *inst)
>  				  num_vpp_pipes, inst->hfi_rc_type);
>  }
>  
> +static inline u32 hfi_buffer_get_recon_count(struct iris_inst *inst)
> +{
> +	u32 num_ref = 1;
> +	u32 ltr_count;
> +
> +	ltr_count = inst->fw_caps[LTR_COUNT].value;
> +
> +	if (ltr_count)
> +		num_ref = num_ref + ltr_count;
> +
> +	return num_ref + 1;
> +}

Here you are always returning num_ref+1 which might break
iris_vpu_enc_scratch2_size calculation since you are using this as common
API for calculating ref buffers. Please recheck.

> +
>  static inline
>  u32 hfi_buffer_comv_enc(u32 frame_width, u32 frame_height, u32 lcu_size,
>  			u32 num_recon, u32 standard)
> @@ -693,17 +706,14 @@ static u32 iris_vpu_enc_comv_size(struct iris_inst *inst)
>  {
>  	u32 height = iris_vpu_enc_get_bitstream_height(inst);
>  	u32 width = iris_vpu_enc_get_bitstream_width(inst);
> -	u32 num_recon = 1;
> -	u32 lcu_size = 16;
> +	u32 num_recon = hfi_buffer_get_recon_count(inst);
> +	u32 standard, lcu_size;
>  
> -	if (inst->codec == V4L2_PIX_FMT_HEVC) {
> -		lcu_size = 32;
> -		return hfi_buffer_comv_enc(width, height, lcu_size,
> -					   num_recon + 1, HFI_CODEC_ENCODE_HEVC);
> -	}
> +	standard = (inst->codec == V4L2_PIX_FMT_HEVC) ?
> +		   HFI_CODEC_ENCODE_HEVC : HFI_CODEC_ENCODE_AVC;
> +	lcu_size = (inst->codec == V4L2_PIX_FMT_HEVC) ? 32 : 16;

these code optimization is not in the scope of this change. pls have in a
spearate patch if needed.

Thanks,
Dikshita
>  
> -	return hfi_buffer_comv_enc(width, height, lcu_size,
> -				   num_recon + 1, HFI_CODEC_ENCODE_AVC);
> +	return hfi_buffer_comv_enc(width, height, lcu_size, num_recon, standard);
>  }
>  
>  static inline
> @@ -1402,10 +1412,9 @@ static u32 iris_vpu_enc_scratch2_size(struct iris_inst *inst)
>  {
>  	u32 frame_height = iris_vpu_enc_get_bitstream_height(inst);
>  	u32 frame_width = iris_vpu_enc_get_bitstream_width(inst);
> -	u32 num_ref = 1;
> +	u32 num_ref = hfi_buffer_get_recon_count(inst);
>  
> -	return hfi_buffer_scratch2_enc(frame_width, frame_height, num_ref,
> -				       false);
> +	return hfi_buffer_scratch2_enc(frame_width, frame_height, num_ref, false);
>  }
>  
>  static u32 iris_vpu_enc_vpss_size(struct iris_inst *inst)
>