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

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Message-ID: <20220706023148.GC2357796@anxtwsw-Precision-3640-Tower>
Date:   Wed, 6 Jul 2022 10:31:48 +0800
From:   Xin Ji <xji@...logixsemi.com>
To:     Hsin-Yi Wang <hsinyi@...omium.org>
Cc:     Robert Foss <robert.foss@...aro.org>,
        Andrzej Hajda <andrzej.hajda@...el.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Sam Ravnborg <sam@...nborg.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Maxime Ripard <maxime@...no.tech>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4] drm/bridge: anx7625: Fix NULL pointer crash when
 using edp-panel

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

Reviewed-by: Xin Ji <xji@...logixsemi.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@...omium.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