linux-kernel - Re: [PATCH v6 14/18] media: verisilicon: vp9: Use destination buffer height to compute chroma offset

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Message-ID: <7da0a2ab-032a-9de9-e136-58f973238c5b@collabora.com>
Date:   Mon, 11 Sep 2023 10:55:02 +0200
From:   Benjamin Gaignard <benjamin.gaignard@...labora.com>
To:     Jernej Škrabec <jernej.skrabec@...il.com>,
        mchehab@...nel.org, tfiga@...omium.org, m.szyprowski@...sung.com,
        ming.qian@....com, ezequiel@...guardiasur.com.ar,
        p.zabel@...gutronix.de, gregkh@...uxfoundation.org,
        hverkuil-cisco@...all.nl, nicolas.dufresne@...labora.com
Cc:     linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-arm-msm@...r.kernel.org,
        linux-rockchip@...ts.infradead.org, linux-staging@...ts.linux.dev,
        kernel@...labora.com
Subject: Re: [PATCH v6 14/18] media: verisilicon: vp9: Use destination buffer
 height to compute chroma offset


Le 10/09/2023 à 15:21, Jernej Škrabec a écrit :
> Hi Benjamin!
>
> Dne petek, 01. september 2023 ob 14:44:10 CEST je Benjamin Gaignard
> napisal(a):
>> Source and destination buffer height may not be the same because
>> alignment constraint are different.
>> Use destination height to compute chroma offset because we target
>> this buffer as hardware output.
>>
>> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@...labora.com>
>> Fixes: e2da465455ce ("media: hantro: Support VP9 on the G2 core")
>> ---
>>   drivers/media/platform/verisilicon/hantro_g2_vp9_dec.c | 4 +---
>>   1 file changed, 1 insertion(+), 3 deletions(-)
>>
>> diff --git a/drivers/media/platform/verisilicon/hantro_g2_vp9_dec.c
>> b/drivers/media/platform/verisilicon/hantro_g2_vp9_dec.c index
>> 6db1c32fce4d..1f3f5e7ce978 100644
>> --- a/drivers/media/platform/verisilicon/hantro_g2_vp9_dec.c
>> +++ b/drivers/media/platform/verisilicon/hantro_g2_vp9_dec.c
>> @@ -93,9 +93,7 @@ static int start_prepare_run(struct hantro_ctx *ctx, const
>> struct v4l2_ctrl_vp9_ static size_t chroma_offset(const struct hantro_ctx
>> *ctx,
>>   			    const struct v4l2_ctrl_vp9_frame
> *dec_params)
>>   {
>> -	int bytes_per_pixel = dec_params->bit_depth == 8 ? 1 : 2;
>> -
>> -	return ctx->src_fmt.width * ctx->src_fmt.height * bytes_per_pixel;
>> +	return ctx->dst_fmt.width * ctx->dst_fmt.height * ctx->bit_depth /
> 8;
>
> Commit message doesn't mention bit_depth change at all. While I think there is
> no difference between dec_params->bit_depth and ctx->bit_depth, you shouldn't
> just use ordinary division. If bit_depth is 10, it will be rounded down. And
> if you decide to use bit_depth from context, please remove dec_params
> argument.

I will change this patch and create a helpers function for chroma and motion vectors
offsets that VP9 and HEVC code will use since they are identical.
I don't see issue with the division. If you have in mind a solution please write it
so I could test it.

Regards,
Benjamin

>
> Best regards,
> Jernej
>
>>   }
>>
>>   static size_t mv_offset(const struct hantro_ctx *ctx,
>
>
>
>