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In-Reply-To: <20220118133759.112458-2-angelogioacchino.delregno@collabora.com>
From:   Chun-Kuang Hu <chunkuang.hu@kernel.org>
Date:   Wed, 26 Jan 2022 00:37:35 +0800
Message-ID: <CAAOTY_9PTK1HoHruvX_6n010aADA5_Rd72TFTMsn4hrH8dts=A@mail.gmail.com>
Subject: Re: [PATCH 2/2] drm: mediatek: mtk_drm_crtc: Use kmalloc in mtk_drm_crtc_duplicate_state
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>
Cc:     Chun-Kuang Hu <chunkuang.hu@kernel.org>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        DRI Development <dri-devel@lists.freedesktop.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@lists.infradead.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Collabora Kernel ML <kernel@collabora.com>
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Hi, AngeloGioacchino:

AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> =E6=96=
=BC
2022=E5=B9=B41=E6=9C=8818=E6=97=A5 =E9=80=B1=E4=BA=8C =E4=B8=8B=E5=8D=889:4=
1=E5=AF=AB=E9=81=93=EF=BC=9A
>
> Optimize mtk_drm_crtc_duplicate_state() by switching from kzalloc() to
> kmalloc(): the only variable of this struct that gets checked in other
> functions is `pending_config`, but if that's set to false, then all of
> the remaining variables will only ever be set, but not read - so, also
> set `pending_config` to false.
> This saves us some small overhead.

Reviewed-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>

>
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@coll=
abora.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_drm_crtc.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c b/drivers/gpu/drm/me=
diatek/mtk_drm_crtc.c
> index 09fc9ad02c7a..f536a0a927e4 100644
> --- a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> +++ b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> @@ -185,7 +185,7 @@ static struct drm_crtc_state *mtk_drm_crtc_duplicate_=
state(struct drm_crtc *crtc
>  {
>         struct mtk_crtc_state *state;
>
> -       state =3D kzalloc(sizeof(*state), GFP_KERNEL);
> +       state =3D kmalloc(sizeof(*state), GFP_KERNEL);
>         if (!state)
>                 return NULL;
>
> @@ -193,6 +193,7 @@ static struct drm_crtc_state *mtk_drm_crtc_duplicate_=
state(struct drm_crtc *crtc
>
>         WARN_ON(state->base.crtc !=3D crtc);
>         state->base.crtc =3D crtc;
> +       state->pending_config =3D false;
>
>         return &state->base;
>  }
> --
> 2.33.1
>