linux-kernel - Re: [PATCH] phy: core: Add consumer device link support

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Date:   Mon, 10 Feb 2020 17:48:26 +0530
From:   Kishon Vijay Abraham I <kishon@...com>
To:     Alexandre Torgue <alexandre.torgue@...com>,
        youling 257 <youling257@...il.com>
CC:     <yoshihiro.shimoda.uh@...esas.com>, <gregkh@...uxfoundation.org>,
        <linux-kernel@...r.kernel.org>, <linux-usb@...r.kernel.org>,
        <saravanak@...gle.com>
Subject: Re: [PATCH] phy: core: Add consumer device link support

Hi,

On 10/02/20 5:00 PM, Alexandre Torgue wrote:
> Hi Kishon,
> 
> On 2/10/20 9:08 AM, Kishon Vijay Abraham I wrote:
>> Hi Alexandre,
>>
>> On 07/02/20 12:27 PM, youling 257 wrote:
>>> test this diff, dwc3 work for my device, thanks.
>>>
>>> 2020-02-07 13:16 GMT+08:00, Kishon Vijay Abraham I <kishon@...com>:
>>>> Hi,
>>>>
>>>> On 06/02/20 7:09 PM, youling257 wrote:
>>>>> This patch cause "dwc3 dwc3.3.auto: failed to create device link to
>>>>> dwc3.3.auto.ulpi" problem.
>>>>> https://bugzilla.kernel.org/show_bug.cgi?id=206435
>>>>
>>>> I'm suspecting there is some sort of reverse dependency with dwc3 ULPI.
>>>> Can you try the following diff?
>>>>
>>>> diff --git a/drivers/phy/phy-core.c b/drivers/phy/phy-core.c
>>>> index 2eb28cc2d2dc..397311dcb116 100644
>>>> --- a/drivers/phy/phy-core.c
>>>> +++ b/drivers/phy/phy-core.c
>>>> @@ -687,7 +687,7 @@ struct phy *phy_get(struct device *dev, const char
>>>> *string)
>>>>
>>>>          get_device(&phy->dev);
>>>>
>>>> -       link = device_link_add(dev, &phy->dev, DL_FLAG_STATELESS);
>>>> +       link = device_link_add(dev, &phy->dev,
>>>> DL_FLAG_SYNC_STATE_ONLY);
>>>>          if (!link) {
>>>>                  dev_err(dev, "failed to create device link to %s\n",
>>>>                          dev_name(phy->dev.parent));
>>>> @@ -802,7 +802,7 @@ struct phy *devm_of_phy_get(struct device *dev,
>>>> struct device_node *np,
>>>>                  return phy;
>>>>          }
>>>>
>>>> -       link = device_link_add(dev, &phy->dev, DL_FLAG_STATELESS);
>>>> +       link = device_link_add(dev, &phy->dev,
>>>> DL_FLAG_SYNC_STATE_ONLY);
>>>>          if (!link) {
>>>>                  dev_err(dev, "failed to create device link to %s\n",
>>>>                          dev_name(phy->dev.parent));
>>>> @@ -851,7 +851,7 @@ struct phy *devm_of_phy_get_by_index(struct device
>>>> *dev, struct device_node *np,
>>>>          *ptr = phy;
>>>>          devres_add(dev, ptr);
>>>>
>>>> -       link = device_link_add(dev, &phy->dev, DL_FLAG_STATELESS);
>>>> +       link = device_link_add(dev, &phy->dev,
>>>> DL_FLAG_SYNC_STATE_ONLY);
>>>>          if (!link) {
>>>>                  dev_err(dev, "failed to create device link to %s\n",
>>>>                          dev_name(phy->dev.parent));Parent
>>
>> Can you check if this doesn't affect the suspend/resume ordering?
> 
> With this fix, suspend/resume ordering is broken on my side. What do you
> think to keep the STATELESS flag and to only display a warn if
> "device_link_add" returns an error ? It's not "smart" but it could
> solved our issue.

yeah, that sounds reasonable for now. Can you find out the dependencies
between dwc3 and ulpi and what exactly breaks. That would help Saravana
to suggest a fix?
> 
> As a lot of improvements have been recently done on device link topic by
> Saravana, we could check with him what is the way to follow.
Thanks
Kishon