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

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Message-ID: <6e75de8187b276f54c8673ccd708b299614bc5c3.camel@mediatek.com>
Date:   Fri, 14 Jan 2022 13:32:02 +0800
From:   Chunfeng Yun <chunfeng.yun@...iatek.com>
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.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()

On Fri, 2022-01-07 at 10:23 +0100, AngeloGioacchino Del Regno wrote:
> 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
> 
Got it, thanks a lot:)

> 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);
> 
>