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Subject: Re: [PATCH] drm: Fix wrong use of connector in vop_get_edp_connector
From:   He Ying <heying24@huawei.com>
To:     <hjc@rock-chips.com>, <heiko@sntech.de>, <airlied@linux.ie>,
        <daniel@ffwll.ch>, <seanpaul@chromium.org>,
        <gustavo.padovan@collabora.com>
CC:     <dri-devel@lists.freedesktop.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-rockchip@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>
References: <20211025015550.66500-1-heying24@huawei.com>
Message-ID: <60f07638-aca2-a1c5-c80e-c5ea4de6b223@huawei.com>
Date:   Tue, 9 Nov 2021 10:06:07 +0800
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kindly ping...

?? 2021/10/25 9:55, He Ying д??:
> >From the comments of drm_for_each_connector_iter(), we know
> that "connector is only valid within the list body, if you
> want to use connector after calling drm_connector_list_iter_end()
> then you need to grab your own reference first using
> drm_connector_get()". So fix the wrong use of connector
> according to the comments and then call drm_connector_put()
> after using connector finishes.
>
> Signed-off-by: He Ying <heying24@huawei.com>
> Fixes: 2cbeb64f6c70 ("drm/rockchip: use drm_for_each_connector_iter()")
> ---
>   drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 9 +++++----
>   1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> index a25b98b7f5bd..469922ad29fa 100644
> --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> @@ -1581,19 +1581,19 @@ static void vop_crtc_reset(struct drm_crtc *crtc)
>   #ifdef CONFIG_DRM_ANALOGIX_DP
>   static struct drm_connector *vop_get_edp_connector(struct vop *vop)
>   {
> -	struct drm_connector *connector;
> +	struct drm_connector *connector = NULL;
>   	struct drm_connector_list_iter conn_iter;
>   
>   	drm_connector_list_iter_begin(vop->drm_dev, &conn_iter);
>   	drm_for_each_connector_iter(connector, &conn_iter) {
>   		if (connector->connector_type == DRM_MODE_CONNECTOR_eDP) {
> -			drm_connector_list_iter_end(&conn_iter);
> -			return connector;
> +			drm_connector_get(connector);
> +			break;
>   		}
>   	}
>   	drm_connector_list_iter_end(&conn_iter);
>   
> -	return NULL;
> +	return connector;
>   }
>   
>   static int vop_crtc_set_crc_source(struct drm_crtc *crtc,
> @@ -1614,6 +1614,7 @@ static int vop_crtc_set_crc_source(struct drm_crtc *crtc,
>   	else
>   		ret = -EINVAL;
>   
> +	drm_connector_put(connector);
>   	return ret;
>   }
>