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Message-ID: <5596626F.5050003@rock-chips.com>
Date: Fri, 03 Jul 2015 18:22:39 +0800
From: Mark yao <mark.yao@rock-chips.com>
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To: Tomasz Figa <tfiga@chromium.org>
CC: dri-devel <dri-devel@lists.freedesktop.org>,
        David Airlie <airlied@linux.ie>, Heiko Stuebner <heiko@sntech.de>,
        Daniel Kurtz <djkurtz@chromium.org>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        Daniel Vetter <daniel@ffwll.ch>, Rob Clark <robdclark@gmail.com>,
        "linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
        "open list:ARM/Rockchip SoC..." <linux-rockchip@lists.infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        sandy.huang@rock-chips.com, dkm@rock-chips.com, zwl@rock-chips.com,
        xw@rock-chips.com
Subject: Re: [PATCH v2 3/5] drm/rockchip: vop: support plane scale
References: <1435313249-4549-1-git-send-email-mark.yao@rock-chips.com> <1435313249-4549-4-git-send-email-mark.yao@rock-chips.com> <CAAFQd5A2j7MXrzOMVnsJr_WUKAFPaicv+r9LgwHccLim4fRk8g@mail.gmail.com> <55965344.5050502@rock-chips.com> <CAAFQd5B3NnUQRqdaXUz6BGCn-5rh1iXnfZXnQRDK3=nF_Ya7SA@mail.gmail.com>
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On 2015年07月03日 17:58, Tomasz Figa wrote:
>>> >>Aren't the scl_modes for CbCr planes always the same as for Y plane?
>> >
>> >
>> >No, such as src(1920 x 1080) -> dst(1280x800), yuv format is NV12.
>> >so Y plane horizontal and vertical is scale down.
>> >
>> >but src_w = 1920 / 2 = 960 < 1280
>> >       src_h = 1080 / 2 = 540 < 800.
>> >
>> >So Cbcr horizontal and vertical is scale up.
> Sorry, I don't follow.
>
> If we scale down Y plane in NV12 from 1920x1080 to 1280x800, then
> original CbCr plane will be 960x540 and destination CbCr plane will be
> 640x400 (because CbCr plane of NV12 is subsampled 2x2, which is half
> the width and half the height of Y plane), so both planes are being
> scaled down.
>
destination CbCr plane is 1280x800, destination can't be subsample.

-- 
Ｍark