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Subject: Re: [PATCH v1 7/9] media: verisilicon: Add Rockchip AV1 decoder
From:   Daniel Almeida <daniel.almeida@collabora.com>
To:     Benjamin Gaignard <benjamin.gaignard@collabora.com>,
        Nicolas Dufresne <nicolas@ndufresne.ca>,
        ezequiel@vanguardiasur.com.ar, p.zabel@pengutronix.de,
        mchehab@kernel.org, robh+dt@kernel.org,
        krzysztof.kozlowski+dt@linaro.org, heiko@sntech.de,
        nicolas.dufresne@collabora.co.uk
Cc:     linux-media@vger.kernel.org, linux-rockchip@lists.infradead.org,
        devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org, kernel@collabora.com
Date:   Fri, 23 Dec 2022 20:20:10 -0300
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Ah, I was too quick on that answer :/

I see that they have REFS_PER_FRAME (7), TOTAL_REFS_PER_FRAME (8) _and_
NUM_REF_FRAMES (8), in which case it is redundant indeed. I will remove
that on v4.

-- Daniel

On Fri, 2022-12-23 at 20:15 -0300, Daniel Almeida wrote:
> > > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0int cur_offset[V4L2_AV1_NU=
M_REF_FRAMES - 1];
> > > +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0int cur_roffset[V4L2_AV1_N=
UM_REF_FRAMES - 1];
> >=20
> > This looks like V4L2_AV1_REFS_PER_FRAME. Daniel, should be remove
> > this
> > V4L2_AV1_NUM_REF_FRAMES ? Its redundant with
> > V4L2_AV1_TOTAL_REFS_PER_FRAME ...
>=20
> Hi. These are different. NUM_REF_FRAMES is the size of the "DPB"
> while
> TOTAL_REFS_PER_FRAME is the maximum number of references a frame can
> use. It just so happens that in AV1 these two are close in absolute
> value (i.e. 7 vs 8).
>=20
> Using VP9 as a comparison, the DPB size is still 8, but
> REFS_PER_FRAME
> is 3 (meaning a frame can specificy LAST, GOLDEN and ALTREF values).
>=20
> As this is per spec and a mere convenience, I vote for keeping it.=20
>=20
> -- Daniel