linux-kernel - Re: [PATCH 1/4] media: qcom: iris: Add intra refresh support for gen1 encoder

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Message-ID: <99609312-bd69-4506-be80-9c6aca6a10ad@oss.qualcomm.com>
Date: Tue, 2 Dec 2025 14:35:15 +0800
From: Wangao Wang <wangao.wang@....qualcomm.com>
To: Bryan O'Donoghue <bod@...nel.org>,
        Vikash Garodia <vikash.garodia@....qualcomm.com>,
        Dikshita Agarwal <dikshita.agarwal@....qualcomm.com>,
        Abhinav Kumar <abhinav.kumar@...ux.dev>,
        Mauro Carvalho Chehab <mchehab@...nel.org>
Cc: wangao.wang@....qualcomm.com, quic_qiweil@...cinc.com,
        Renjiang Han <renjiang.han@....qualcomm.com>,
        linux-media@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/4] media: qcom: iris: Add intra refresh support for gen1
 encoder



On 2025/11/27 18:35, Bryan O'Donoghue wrote:
> On 27/11/2025 07:44, Wangao Wang wrote:
>> +    hfi_val.mbs = fmt->width * fmt->height;
>> +    hfi_val.mbs /= 16 * 16;
> 
> 256
> 
> But why ? Also why express it as 16 * 16 ?
> 
>> +    if (hfi_val.mbs % ir_period)
>> +        hfi_val.mbs++;
>> +    hfi_val.mbs /= ir_period;
> 
> This code deserves some commentary.
> 
> ---
> bod

16 * 16 is the size of a macroblock.

Here, we first calculate the total number of macroblocks in one frame, 
then determine the number of macroblocks that need intra refresh in each 
frame based on the ir_period. All macroblocks must be refreshed within a 
single ir_period.

However, there is an issue: the macroblock sizes for AVC and HEVC are 
different. I will address this in a later patch and add comments 
accordingly.

-- 
Best Regards,
Wangao