linux-kernel - Re: [PATCH v2] drm/rockchip: vop: Disable planes when disabling CRTC

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Message-ID: <56F8D1A4.2080603@rock-chips.com>
Date:	Mon, 28 Mar 2016 14:39:32 +0800
From:	Mark yao <mark.yao@...k-chips.com>
To:	Tomeu Vizoso <tomeu.vizoso@...labora.com>,
	linux-kernel@...r.kernel.org
CC:	David Airlie <airlied@...ux.ie>, Heiko Stuebner <heiko@...ech.de>,
	dri-devel@...ts.freedesktop.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-rockchip@...ts.infradead.org
Subject: Re: [PATCH v2] drm/rockchip: vop: Disable planes when disabling CRTC

On 2016年03月22日 23:08, Tomeu Vizoso wrote:
> When a VOP is re-enabled, it will start scanning right away the
> framebuffers that were configured from the last time, even if those have
> been destroyed already.
>
> To prevent the VOP from trying to access freed memory, disable all its
> windows when the CRTC is being disabled, then each window will get a
> valid framebuffer address before it's enabled again.
>
> Signed-off-by: Tomeu Vizoso <tomeu.vizoso@...labora.com>
> Link: http://lkml.kernel.org/g/CAAObsKAv+05ih5U+=4kic_NsjGMhfxYheHR8xXXmacZs+p5SHw@mail.gmail.com
> ---
>   drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 15 +++++++++++++++
>   1 file changed, 15 insertions(+)
>
> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> index 5e57f5b2e4b0..e2118e62345b 100644
> --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> @@ -499,10 +499,25 @@ err_disable_hclk:
>   static void vop_crtc_disable(struct drm_crtc *crtc)
>   {
>   	struct vop *vop = to_vop(crtc);
> +	int i;
>   
>   	if (!vop->is_enabled)
>   		return;
>   
> +	/*
> +	 * We need to make sure that all windows are disabled before we
> +	 * disable that crtc. Otherwise we might try to scan from a destroyed
> +	 * buffer later.
> +	 */
> +	for (i = 0; i < vop->data->win_size; i++) {
> +		struct vop_win *vop_win = &vop->win[i];
> +		const struct vop_win_data *win = vop_win->data;
> +
> +		spin_lock(&vop->reg_lock);
> +		VOP_WIN_SET(vop, win, enable, 0);
> +		spin_unlock(&vop->reg_lock);
> +	}
> +
>   	drm_crtc_vblank_off(crtc);
>   
>   	/*
Looks good for me, and it works on my board.

Applied to my drm-fixes.

Thanks

-- 
Ｍark Yao