Re: [RESEND PATCH 1/3] drm/mediatek: mtk_dpi: Rename bridge to next_bridge

[Boris Brezillon]

On Mon, 18 May 2020 19:39:07 +0200
Enric Balletbo i Serra <enric.balletbo@xxxxxxxxxxxxx> wrote:

> This is really a cosmetic change just to make a bit more readable the
> code after convert the driver to drm_bridge. The bridge variable name
> will be used by the encoder drm_bridge, and the chained bridge will be
> named next_bridge.
> 
> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@xxxxxxxxxxxxx>
> Reviewed-by: Chun-Kuang Hu <chunkuang.hu@xxxxxxxxxx>
> ---
> 
>  drivers/gpu/drm/mediatek/mtk_dpi.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_dpi.c b/drivers/gpu/drm/mediatek/mtk_dpi.c
> index 7fbfa95bab09..7112125dc3d1 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dpi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dpi.c
> @@ -61,7 +61,7 @@ enum mtk_dpi_out_color_format {
>  struct mtk_dpi {
>  	struct mtk_ddp_comp ddp_comp;
>  	struct drm_encoder encoder;
> -	struct drm_bridge *bridge;
> +	struct drm_bridge *next_bridge;

Did you consider moving the drm_of_find_panel_or_bridge() call to
mtk_dpi_bind() so you can get rid of this field?

This makes we realize there's no refcounting on bridges, which means
the bridge can vanish between the drm_of_find_panel_or_bridge() and
drm_bridge_attach() calls :-/.

>  	void __iomem *regs;
>  	struct device *dev;
>  	struct clk *engine_clk;
> @@ -607,7 +607,7 @@ static int mtk_dpi_bind(struct device *dev, struct device *master, void *data)
>  	/* Currently DPI0 is fixed to be driven by OVL1 */
>  	dpi->encoder.possible_crtcs = BIT(1);
>  
> -	ret = drm_bridge_attach(&dpi->encoder, dpi->bridge, NULL, 0);
> +	ret = drm_bridge_attach(&dpi->encoder, dpi->next_bridge, NULL, 0);
>  	if (ret) {
>  		dev_err(dev, "Failed to attach bridge: %d\n", ret);
>  		goto err_cleanup;
> @@ -747,11 +747,11 @@ static int mtk_dpi_probe(struct platform_device *pdev)
>  	}
>  
>  	ret = drm_of_find_panel_or_bridge(dev->of_node, 0, 0,
> -					  NULL, &dpi->bridge);
> +					  NULL, &dpi->next_bridge);
>  	if (ret)
>  		return ret;
>  
> -	dev_info(dev, "Found bridge node: %pOF\n", dpi->bridge->of_node);
> +	dev_info(dev, "Found bridge node: %pOF\n", dpi->next_bridge->of_node);
>  
>  	comp_id = mtk_ddp_comp_get_id(dev->of_node, MTK_DPI);
>  	if (comp_id < 0) {