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

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Message-ID: <a2d7953e-6434-bdb1-34bd-779a3fb11f58@socionext.com>
Date:   Tue, 8 Sep 2020 01:09:12 +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

Hi Rob,

On 2020/09/04 7:25, Rob Herring wrote:
> On Fri, Aug 21, 2020 at 1:05 AM Kunihiko Hayashi
> <hayashi.kunihiko@...ionext.com> wrote:
>>
>> 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?
> 
> Nevermind. I was thinking we had some error prints for the optional
> vs. non-optional variants.
I understand.
As long as this phy is "optional", this doesn't need to print error message.
Once I cancel this patch, and leave the phy as "optional".

Thank you,

---
Best Regards
Kunihiko Hayashi