linux-kernel - Re: [PATCH v2 1/1] drm/bridge: imx93-mipi-dsi: Use dev_err

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Message-ID: <cc553f61-e494-45c0-84e9-8a0e275ba416@nxp.com>
Date: Wed, 29 May 2024 16:32:31 +0800
From: Liu Ying <victor.liu@....com>
To: Alexander Stein <alexander.stein@...tq-group.com>,
 Andrzej Hajda <andrzej.hajda@...el.com>,
 Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>,
 Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
 Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
 Shawn Guo <shawnguo@...nel.org>, Sascha Hauer <s.hauer@...gutronix.de>,
 Pengutronix Kernel Team <kernel@...gutronix.de>,
 Fabio Estevam <festevam@...il.com>
Cc: dri-devel@...ts.freedesktop.org, imx@...ts.linux.dev,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/1] drm/bridge: imx93-mipi-dsi: Use dev_err_probe

On 05/29/2024, Alexander Stein wrote:
> Hi,
> 
> Am Mittwoch, 29. Mai 2024, 09:50:24 CEST schrieb Liu Ying:
>> On 05/29/2024, Alexander Stein wrote:
>>> Although very unlike to occur (media_blk_ctrl needs 'syscon' compatible
>>> removed), it lines up with the other error paths in probe function.
>>
>> Why media_blk_ctrl needs 'syscon' compatible removed?
> 
> No, it does not. As media_blk_ctrl is also used as power-domain the device
> will not even be probed if media_blk_ctrl is not available.
> I just mentioned it under which conditions this error path could happen.

The error path you mentioned returns ERR_PTR(-EINVAL) which
doesn't make sense to use dev_err_probe.  ERR_PTR(-EPROBE_DEFER)
is the one in question.

> 
> Best regards,
> Alexander
> 
>> device_node_get_regmap may return error pointer other than
>> ERR_PTR(-EPROBE_DEFER), like ERR_PTR(-ENOMEM).
>>
>> struct regmap *syscon_node_to_regmap(struct device_node *np)                     
>> {                                                                                
>>         if (!of_device_is_compatible(np, "syscon"))                              
>>                 return ERR_PTR(-EINVAL);                                         
>>                                                                                  
>>         return device_node_get_regmap(np, true);                                 
>> }                                                                                
>> EXPORT_SYMBOL_GPL(syscon_node_to_regmap);
>>
>> Regard,
>> Liu Ying
>>
>>>
>>> Signed-off-by: Alexander Stein <alexander.stein@...tq-group.com>
>>> ---
>>> Changes in v2:
>>> * Removed unused variable
>>> * Added missing \n at end of string
>>>
>>>  drivers/gpu/drm/bridge/imx/imx93-mipi-dsi.c | 9 +++------
>>>  1 file changed, 3 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/bridge/imx/imx93-mipi-dsi.c b/drivers/gpu/drm/bridge/imx/imx93-mipi-dsi.c
>>> index 2347f8dd632f9..13025f47f3902 100644
>>> --- a/drivers/gpu/drm/bridge/imx/imx93-mipi-dsi.c
>>> +++ b/drivers/gpu/drm/bridge/imx/imx93-mipi-dsi.c
>>> @@ -834,18 +834,15 @@ static int imx93_dsi_probe(struct platform_device *pdev)
>>>  	struct device *dev = &pdev->dev;
>>>  	struct device_node *np = dev->of_node;
>>>  	struct imx93_dsi *dsi;
>>> -	int ret;
>>>  
>>>  	dsi = devm_kzalloc(dev, sizeof(*dsi), GFP_KERNEL);
>>>  	if (!dsi)
>>>  		return -ENOMEM;
>>>  
>>>  	dsi->regmap = syscon_regmap_lookup_by_phandle(np, "fsl,media-blk-ctrl");
>>> -	if (IS_ERR(dsi->regmap)) {
>>> -		ret = PTR_ERR(dsi->regmap);
>>> -		dev_err(dev, "failed to get block ctrl regmap: %d\n", ret);
>>> -		return ret;
>>> -	}
>>> +	if (IS_ERR(dsi->regmap))
>>> +		return dev_err_probe(dev, PTR_ERR(dsi->regmap),
>>> +				     "failed to get block ctrl regmap\n");
>>>  
>>>  	dsi->clk_pixel = devm_clk_get(dev, "pix");
>>>  	if (IS_ERR(dsi->clk_pixel))
>>
>>
> 
> 
-- 
Regards,
Liu Ying