linux-kernel - Re: [PATCH v3 2/3] ata: ahci

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Date:	Wed, 08 Jan 2014 14:14:18 +0100
From:	Hans de Goede <hdegoede@...hat.com>
To:	Roger Quadros <rogerq@...com>, Arnd Bergmann <arnd@...db.de>,
	Kishon Vijay Abraham I <kishon@...com>
CC:	tj@...nel.org, sergei.shtylyov@...entembedded.com,
	b.zolnierkie@...sung.com, linux-ide@...r.kernel.org,
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
	Balaji T K <balajitk@...com>
Subject: Re: [PATCH v3 2/3] ata: ahci_platform: Manage SATA PHY

Hi,

On 01/08/2014 12:28 PM, Roger Quadros wrote:
> On 01/08/2014 03:35 PM, Arnd Bergmann wrote:
>> On Wednesday 08 January 2014 15:29:18 Kishon Vijay Abraham I wrote:
>>>> +     hpriv->phy = devm_phy_get(dev, "sata-phy");
>>>> +     if (IS_ERR(hpriv->phy)) {
>>>> +             dev_dbg(dev, "can't get sata-phy\n");
>>>> +             /* return only if -EPROBE_DEFER */
>>>> +             if (PTR_ERR(hpriv->phy) == -EPROBE_DEFER) {
>>>> +                     rc = -EPROBE_DEFER;
>>>> +                     goto disable_unprepare_clk;
>>>> +             }
>>>> +     }
>>
>> This should probably check for all errors except "not present"
>> rather than checking for -EPROBE_DEFER. We want to abort the
>> probe function for deferred probe as well as the case where we
>> a PHY was listed but isn't working properly.
>
> OK.
>
>>
>>>> +     if (!IS_ERR(hpriv->phy)) {
>>>> +             phy_init(hpriv->phy);
>>>
>>> Don't we have to check the return values of phy_init and phy_power_on? Is it
>>> not needed because it is an optional phy?
>>
>> Right. I think we should set hpriv->phy to NULL if it's not there and
>> then call the functions only if it's actually present but bail out on
>> an error.
>
> OK. How does this look?
>
> hpriv->phy = devm_phy_get(dev, "sata-phy");
> if (IS_ERR(hpriv->phy)) {
> 	if (PTR_ERR(hpriv->phy) == -ENODEV)
> 		goto continue;

-ENODEV is not the right errno to check for,
if there is no phy specified in the dt then
you will get -EINVAL (no phy-names property) or
-ENODATA (phy-names property is there but name
not found).

Also you don't want to log an error on
PROBE_DEFERRAL.

Here is what I've for similar code I'm working on
for ehci-platform.c and ohci-platform.c :

                 priv->phy = devm_phy_get(&dev->dev, "phy0");
                 if (IS_ERR(priv->phy)) {
                         err = PTR_ERR(priv->phy);
                         if (err != -EINVAL && err != -ENODATA) {
                                 if (err != -EPROBE_DEFER)
                                         dev_err(&dev->dev,
                                                 "Error getting phy\n");
                                 goto err_put_hcd;
                         }
                         priv->phy = NULL;
                 }

And from then on I simply use "if (priv->phy)" checks, and of course
check phy_init and phy_power_on return values.

Regards,

Hans
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