linux-kernel - Re: [PATCH v2 RESEND] usb: dwc3: core: Fix ULPI PHYs and prevent phy_get/ulpi

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Message-ID: <ca6e775c-98ce-abab-56e1-e40e673dd111@linaro.org>
Date:   Mon, 26 Nov 2018 19:14:22 +0200
From:   Todor Tomov <todor.tomov@...aro.org>
To:     Felipe Balbi <balbi@...nel.org>
Cc:     Roger Quadros <rogerq@...com>, linux-usb@...r.kernel.org,
        vigneshr@...com, gregkh@...uxfoundation.org,
        linux-kernel@...r.kernel.org,
        "linux-stable # = v4 . 13" <stable@...r.kernel.org>
Subject: Re: [PATCH v2 RESEND] usb: dwc3: core: Fix ULPI PHYs and prevent
 phy_get/ulpi_init during suspend/resume

Hi Felipe,

On 26.11.2018 10:27, Todor Tomov wrote:
> Hi Felipe,
> 
> On 16.11.2018 19:01, Todor Tomov wrote:
>> Hi,
>>
>> On 15.11.2018 10:09, Felipe Balbi wrote:
>>>
>>> Hi,
>>>
>>> Todor Tomov <todor.tomov@...aro.org> writes:
>>>
>>>> Hello,
>>>>
>>>> After I apply this patch on 4.14 (or receive it with 4.14.70) I see a regression with
>>>> the Qualcomm QUSB2 phy driver. I'm testing on a Dragonboard 820c.
>>>> In boot log I get:
>>>>
>>>> [    4.525502] phy phy-7412000.phy.6: QUSB2PHY pll lock failed: status reg = 0
>>>> [    4.529232] phy phy-7412000.phy.6: phy init failed --> -16
>>>> [    4.536170] dwc3 7600000.dwc3: failed to initialize core
>>>> [    4.541743] dwc3: probe of 7600000.dwc3 failed with error -16
>>>> [    4.549979] phy phy-7411000.phy.5: QUSB2PHY pll lock failed: status reg = 0
>>>> [    4.552843] phy phy-7411000.phy.5: phy init failed --> -16
>>>> [    4.559606] dwc3 6a00000.dwc3: failed to initialize core
>>>> [    4.565181] dwc3: probe of 6a00000.dwc3 failed with error -16
>>>>
>>>> I can provide a full log if needed.
>>>
>>> please do. Also, try mainline and let us know if the problem
>>
>> This is the full log on 4.14.69 + this patch: https://paste.ubuntu.com/p/N5WdHw47QC/
>> I also managed to get a log from 4.20.0-rc2 and I see the same error: https://paste.udwc3_phy_setupbuntu.com/p/jz6fvYyZh6/
>>
>>> persists. Why do you get -EBUSY from the PHY driver?
>>
>> Maybe I could have proposed a fix if I knew but I don't know.
> 
> I have done some debugging but I still cannot understand it completely.
> 
> What I see is that if the PHY interface is configured first (dwc3_phy_setup)
> then the PHY init (qusb2_phy_init called by dwc3_core_soft_reset) fails
> with "pll lock failed". If we move dwc3_phy_setup after dwc3_core_soft_reset
> as it was before this patch, it works.

I have found that during dwc3_phy_setup the PHY interface is configured
to suspend and this is what breaks the QUSB2 PHY initialization.
It seems that it can be fixed by adding the "snps,dis_u2_susphy_quirk"
quirk in device tree. If this approach proves correct, I'll send the
patch upstream.

Best regards,
Todor

> 
> Do you have any ideas why this happens or how to solve it?
> 
> Thank you.
> Best regards,
> Todor
>