linux-kernel - Re: [PATCH] drm/bridge: analogix_dp: Fix bailout for devm_drm_bridge

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Message-ID: <b5556cbe-76ed-4ddd-9b76-5896c2e1520c@nxp.com>
Date: Wed, 6 Aug 2025 17:38:17 +0800
From: Liu Ying <victor.liu@....com>
To: Luca Ceresoli <luca.ceresoli@...tlin.com>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
 andrzej.hajda@...el.com, neil.armstrong@...aro.org, rfoss@...nel.org,
 Laurent.pinchart@...asonboard.com, jonas@...boo.se,
 jernej.skrabec@...il.com, maarten.lankhorst@...ux.intel.com,
 mripard@...nel.org, tzimmermann@...e.de, airlied@...il.com, simona@...ll.ch,
 dmitry.baryshkov@....qualcomm.com, dianders@...omium.org,
 damon.ding@...k-chips.com, m.szyprowski@...sung.com
Subject: Re: [PATCH] drm/bridge: analogix_dp: Fix bailout for
 devm_drm_bridge_alloc()

On 08/06/2025, Luca Ceresoli wrote:
> Hello Liu,
> 
> On Wed,  6 Aug 2025 16:54:24 +0800
> Liu Ying <victor.liu@....com> wrote:
> 
>> devm_drm_bridge_alloc() returns ERR_PTR on failure instead of a
>> NULL pointer, so use IS_ERR() to check the returned pointer.
>>
>> Fixes: 48f05c3b4b70 ("drm/bridge: analogix_dp: Use devm_drm_bridge_alloc() API")
>> Signed-off-by: Liu Ying <victor.liu@....com>
>> ---
>>  drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
>> index ed35e567d117..86cf898a09bb 100644
>> --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
>> +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
>> @@ -1474,7 +1474,7 @@ analogix_dp_probe(struct device *dev, struct analogix_dp_plat_data *plat_data)
>>  
>>  	dp = devm_drm_bridge_alloc(dev, struct analogix_dp_device, bridge,
>>  				   &analogix_dp_bridge_funcs);
>> -	if (!dp)
>> +	if (IS_ERR(dp))
>>  		return ERR_PTR(-ENOMEM);
> 
> Good catch, thanks!
> 
> You fix is correct but now I realized one additional fix is needed in
> the following line:
> 
> -		return ERR_PTR(-ENOMEM);
> +		return ERR_PTR(dp);

You mean ERR_CAST(dp)?

> 
> Can you send a v2 with that fixed?

I find devm_drm_bridge_alloc() always returns ERR_PTR(-ENOMEM) in this
driver context, so it seems fine to keep the existing ERR_PTR(-ENOMEM).
If you prefer ERR_CAST(dp), I may send v2 to use ERR_CAST(dp).

> 
> Luca
> 


-- 
Regards,
Liu Ying