linux-kernel - Re: [PATCH v6 6/6] PCI: uniphier: Add error message when failed to get phy

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Date:   Fri, 21 Aug 2020 16:05:21 +0900
From:   Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>
To:     Rob Herring <robh+dt@...nel.org>
Cc:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Jingoo Han <jingoohan1@...il.com>,
        Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Marc Zyngier <maz@...nel.org>, PCI <linux-pci@...r.kernel.org>,
        devicetree@...r.kernel.org,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Masami Hiramatsu <masami.hiramatsu@...aro.org>,
        Jassi Brar <jaswinder.singh@...aro.org>
Subject: Re: [PATCH v6 6/6] PCI: uniphier: Add error message when failed to
 get phy

On 2020/08/18 1:39, Rob Herring wrote:
> On Fri, Aug 7, 2020 at 4:25 AM Kunihiko Hayashi
> <hayashi.kunihiko@...ionext.com> wrote:
>>
>> Even if phy driver doesn't probe, the error message can't be distinguished
>> from other errors. This displays error message caused by the phy driver
>> explicitly.
>>
>> Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>
>> ---
>>   drivers/pci/controller/dwc/pcie-uniphier.c | 8 ++++++--
>>   1 file changed, 6 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/pci/controller/dwc/pcie-uniphier.c b/drivers/pci/controller/dwc/pcie-uniphier.c
>> index 93ef608..7c8721e 100644
>> --- a/drivers/pci/controller/dwc/pcie-uniphier.c
>> +++ b/drivers/pci/controller/dwc/pcie-uniphier.c
>> @@ -489,8 +489,12 @@ static int uniphier_pcie_probe(struct platform_device *pdev)
>>                  return PTR_ERR(priv->rst);
>>
>>          priv->phy = devm_phy_optional_get(dev, "pcie-phy");
> 
> The point of the optional variant vs. devm_phy_get() is whether or not
> you get an error message. So shouldn't you switch to devm_phy_get
> instead?
> 
>> -       if (IS_ERR(priv->phy))
>> -               return PTR_ERR(priv->phy);
>> +       if (IS_ERR(priv->phy)) {
>> +               ret = PTR_ERR(priv->phy);
>> +               if (ret != -EPROBE_DEFER)
>> +                       dev_err(dev, "Failed to get phy (%d)\n", ret);
>> +               return ret;
>> +       }

The 'phys' property is optional, so if there isn't 'phys' in the PCIe node,
devm_phy_get() returns -ENODEV, and devm_phy_optional_get() returns NULL.

When devm_phy_optional_get() replaces devm_phy_get(),
condition for displaying an error message changes to:

    (ret != -EPROBE_DEFER && ret != -ENODEV)

This won't be simple, but should it be replaced?

Thank you,

---
Best Regards
Kunihiko Hayashi