Re: [PATCH 3/4] drm/bridge: anx7625: Fix NULL pointer crash when using edp-panel

From: Xin Ji <xji@analogixsemi.com>
To: Hsin-Yi Wang <hsinyi@chromium.org>
Cc: Robert Foss <robert.foss@linaro.org>,
	Andrzej Hajda <andrzej.hajda@intel.com>,
	Neil Armstrong <narmstrong@baylibre.com>,
	Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
	Jonas Karlman <jonas@kwiboo.se>,
	Jernej Skrabec <jernej.skrabec@gmail.com>,
	David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
	Sam Ravnborg <sam@ravnborg.org>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	Maxime Ripard <maxime@cerno.tech>,
	dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/4] drm/bridge: anx7625: Fix NULL pointer crash when using edp-panel
Date: Wed, 6 Jul 2022 10:31:48 +0800	[thread overview]
Message-ID: <20220706023148.GC2357796@anxtwsw-Precision-3640-Tower> (raw)
In-Reply-To: <20220629160550.433980-4-hsinyi@chromium.org>

Hi Hsin-Yi, thanks for your patch, it looks good to me.

Reviewed-by: Xin Ji <xji@analogixsemi.com>

Thanks,
Xin

On Thu, Jun 30, 2022 at 12:05:49AM +0800, Hsin-Yi Wang wrote:
> Move devm_of_dp_aux_populate_ep_devices() after pm runtime and i2c setup
> to avoid NULL pointer crash.
> 
> edp-panel probe (generic_edp_panel_probe) calls pm_runtime_get_sync() to
> read EDID. At this time, bridge should have pm runtime enabled and i2c
> clients ready.
> 
> Fixes: adca62ec370c ("drm/bridge: anx7625: Support reading edid through aux channel")
> Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
> ---
>  drivers/gpu/drm/bridge/analogix/anx7625.c | 17 +++++++++--------
>  1 file changed, 9 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.c b/drivers/gpu/drm/bridge/analogix/anx7625.c
> index 478f5af381c7d..59ddeba33652b 100644
> --- a/drivers/gpu/drm/bridge/analogix/anx7625.c
> +++ b/drivers/gpu/drm/bridge/analogix/anx7625.c
> @@ -2590,14 +2590,6 @@ static int anx7625_i2c_probe(struct i2c_client *client,
>  	platform->aux.dev = dev;
>  	platform->aux.transfer = anx7625_aux_transfer;
>  	drm_dp_aux_init(&platform->aux);
> -	devm_of_dp_aux_populate_ep_devices(&platform->aux);
> -
> -	ret = anx7625_parse_dt(dev, pdata);
> -	if (ret) {
> -		if (ret != -EPROBE_DEFER)
> -			DRM_DEV_ERROR(dev, "fail to parse DT : %d\n", ret);
> -		goto free_wq;
> -	}
>  
>  	if (anx7625_register_i2c_dummy_clients(platform, client) != 0) {
>  		ret = -ENOMEM;
> @@ -2613,6 +2605,15 @@ static int anx7625_i2c_probe(struct i2c_client *client,
>  	if (ret)
>  		goto free_wq;
>  
> +	devm_of_dp_aux_populate_ep_devices(&platform->aux);
> +
> +	ret = anx7625_parse_dt(dev, pdata);
> +	if (ret) {
> +		if (ret != -EPROBE_DEFER)
> +			DRM_DEV_ERROR(dev, "fail to parse DT : %d\n", ret);
> +		goto free_wq;
> +	}
> +
>  	if (!platform->pdata.low_power_mode) {
>  		anx7625_disable_pd_protocol(platform);
>  		pm_runtime_get_sync(dev);
> -- 
> 2.37.0.rc0.161.g10f37bed90-goog