linux-kernel - Re: [PATCH 2/2] drm: mediatek: mtk_drm_crtc: Use kmalloc in mtk_drm_crtc_duplicate

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

Hi, AngeloGioacchino:

AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com> 於
2022年1月18日 週二 下午9:41寫道：
>
> 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@...nel.org>

>
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.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/mediatek/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 = kzalloc(sizeof(*state), GFP_KERNEL);
> +       state = 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 != crtc);
>         state->base.crtc = crtc;
> +       state->pending_config = false;
>
>         return &state->base;
>  }
> --
> 2.33.1
>