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Date:   Thu, 25 Apr 2019 12:20:33 +0300
From:   Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To:     Matt Redfearn <matt.redfearn@thinci.com>
Cc:     Andrzej Hajda <a.hajda@samsung.com>,
        Philippe Cornu <philippe.cornu@st.com>,
        "dri-devel@lists.freedesktop.org" <dri-devel@lists.freedesktop.org>,
        Matthew Redfearn <matthew.redfearn@thinci.com>,
        Nickey Yang <nickey.yang@rock-chips.com>,
        Heiko Stuebner <heiko@sntech.de>,
        Archit Taneja <architt@codeaurora.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>
Subject: Re: [PATCH] drm/bridge/synopsys: dsi: Don't blindly call post_disable
Message-ID: <20190425092033.GB4557@pendragon.ideasonboard.com>
References: <20190424142148.25927-1-matt.redfearn@thinci.com>
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Hi Matt,

Thank you for the patch.

On Wed, Apr 24, 2019 at 02:22:00PM +0000, Matt Redfearn wrote:
> The DRM documentation states that post_disable is an optional callback.
> As such an implementing device may not populate it. To avoid panicing
> the kernel by calling a NULL function pointer, we should NULL check it
> before blindy calling it.
> 
> Signed-off-by: Matt Redfearn <matt.redfearn@thinci.com>

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> ---
> 
>  drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
> index 38e88071363..0ee440216b8 100644
> --- a/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
> +++ b/drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c
> @@ -805,7 +805,8 @@ static void dw_mipi_dsi_bridge_post_disable(struct drm_bridge *bridge)
>  	 * This needs to be fixed in the drm_bridge framework and the API
>  	 * needs to be updated to manage our own call chains...
>  	 */
> -	dsi->panel_bridge->funcs->post_disable(dsi->panel_bridge);
> +	if (dsi->panel_bridge->funcs->post_disable)
> +		dsi->panel_bridge->funcs->post_disable(dsi->panel_bridge);
>  
>  	if (dsi->slave) {
>  		dw_mipi_dsi_disable(dsi->slave);

-- 
Regards,

Laurent Pinchart