linux-kernel - Re: [PATCH 3/3] phy: mediatek: phy-mtk-mipi-dsi: Simplify with dev_err

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Date:   Fri, 7 Jan 2022 10:23:32 +0100
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Chunfeng Yun <chunfeng.yun@...iatek.com>, chunkuang.hu@...nel.org
Cc:     p.zabel@...gutronix.de, kishon@...com, vkoul@...nel.org,
        matthias.bgg@...il.com, dri-devel@...ts.freedesktop.org,
        linux-mediatek@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-phy@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] phy: mediatek: phy-mtk-mipi-dsi: Simplify with
 dev_err_probe()

Il 06/01/22 10:13, Chunfeng Yun ha scritto:
> On Mon, 2022-01-03 at 15:53 +0100, AngeloGioacchino Del Regno wrote:
>> Use the dev_err_probe() helper to simplify error handling during
>> probe.
>>
>> Signed-off-by: AngeloGioacchino Del Regno <
>> angelogioacchino.delregno@...labora.com>
>> ---
>>   drivers/phy/mediatek/phy-mtk-mipi-dsi.c | 29 +++++++++------------
>> ----
>>   1 file changed, 10 insertions(+), 19 deletions(-)
>>
>> diff --git a/drivers/phy/mediatek/phy-mtk-mipi-dsi.c
>> b/drivers/phy/mediatek/phy-mtk-mipi-dsi.c
>> index 6f7425b0bf5b..4b77508f5241 100644
>> --- a/drivers/phy/mediatek/phy-mtk-mipi-dsi.c
>> +++ b/drivers/phy/mediatek/phy-mtk-mipi-dsi.c
>> @@ -148,11 +148,9 @@ static int mtk_mipi_tx_probe(struct
>> platform_device *pdev)
>>   		return PTR_ERR(mipi_tx->regmap);
>>   
>>   	ref_clk = devm_clk_get(dev, NULL);
>> -	if (IS_ERR(ref_clk)) {
>> -		ret = PTR_ERR(ref_clk);
>> -		dev_err(dev, "Failed to get reference clock: %d\n",
>> ret);
>> -		return ret;
>> -	}
>> +	if (IS_ERR(ref_clk))
>> +		return dev_err_probe(dev, PTR_ERR(ref_clk),
>> +				     "Failed to get reference
>> clock\n");
>>   
>>   	ret = of_property_read_u32(dev->of_node, "drive-strength-
>> microamp",
>>   				   &mipi_tx->mipitx_drive);
>> @@ -172,27 +170,20 @@ static int mtk_mipi_tx_probe(struct
>> platform_device *pdev)
>>   
>>   	ret = of_property_read_string(dev->of_node, "clock-output-
>> names",
>>   				      &clk_init.name);
>> -	if (ret < 0) {
>> -		dev_err(dev, "Failed to read clock-output-names: %d\n",
>> ret);
>> -		return ret;
>> -	}
>> +	if (ret < 0)
>> +		return dev_err_probe(dev, ret, "Failed to read clock-
>> output-names\n");
> Seems no need change it here. (no EPROBE_DEFER error)
> 

Hello Chunfeng,

pasting from kernel driver-api infrastructure guidelines:

[...]Note that it is deemed acceptable to use this function for error prints during 
probe even if the err is known to never be -EPROBE_DEFER. The benefit compared to a 
normal dev_err() is the standardized format of the error code and the fact that the 
error code is returned.

https://www.kernel.org/doc/html/latest/driver-api/infrastructure.html

Regards,
- Angelo

> Thanks
>>   
>>   	clk_init.ops = mipi_tx->driver_data->mipi_tx_clk_ops;
>>   
>>   	mipi_tx->pll_hw.init = &clk_init;
>>   	mipi_tx->pll = devm_clk_register(dev, &mipi_tx->pll_hw);
>> -	if (IS_ERR(mipi_tx->pll)) {
>> -		ret = PTR_ERR(mipi_tx->pll);
>> -		dev_err(dev, "Failed to register PLL: %d\n", ret);
>> -		return ret;
>> -	}
>> +	if (IS_ERR(mipi_tx->pll))
>> +		return dev_err_probe(dev, PTR_ERR(mipi_tx->pll),
>> "Cannot register PLL\n");
>>   
>>   	phy = devm_phy_create(dev, NULL, &mtk_mipi_tx_ops);
>> -	if (IS_ERR(phy)) {
>> -		ret = PTR_ERR(phy);
>> -		dev_err(dev, "Failed to create MIPI D-PHY: %d\n", ret);
>> -		return ret;
>> -	}
>> +	if (IS_ERR(phy))
>> +		return dev_err_probe(dev, PTR_ERR(phy), "Failed to
>> create MIPI D-PHY\n");
>> +
>>   	phy_set_drvdata(phy, mipi_tx);
>>   
>>   	phy_provider = devm_of_phy_provider_register(dev,
>> of_phy_simple_xlate);
>