linux-kernel - Re: [PATCH] usb: dwc3: core: Don't try to get PHYs during suspend/resume

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Date:   Wed, 10 Jan 2018 16:04:15 +0200
From:   Felipe Balbi <balbi@...nel.org>
To:     Roger Quadros <rogerq@...com>
Cc:     vigneshr@...com, gregkh@...uxfoundation.org,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        "linux-stable # \= v4 . 13" <stable@...r.kernel.org>
Subject: Re: [PATCH] usb: dwc3: core: Don't try to get PHYs during suspend/resume


Hi,

Roger Quadros <rogerq@...com> writes:
>> Roger Quadros <rogerq@...com> writes:
>>> Felipe,
>>>
>>> On 10/01/18 15:11, Roger Quadros wrote:
>>>> The USB PHYs should be requested only once during the life cycle of
>>>> this driver.
>>>>
>>>> As dwc3_core_init() is called during system suspend/resume
>>>> it will result in multiple calls to dwc3_core_get_phy() which is wrong.
>>>>
>>>> To prevent that let's move dwc3_core_get_phy() call
>>>> outside dwc3_core_init().
>>>>
>>>> Fixes: 541768b08a4 ("usb: dwc3: core: Call dwc3_core_get_phy() before initializing phys")
>>>> Cc: linux-stable <stable@...r.kernel.org> # >= v4.13
>>>> Signed-off-by: Roger Quadros <rogerq@...com>
>>>
>>> FYI. this patch brings the code back to
>>> revert 541768b08a40	("usb: dwc3: core: Call dwc3_core_get_phy() before initializing phys")
>>> revert f54edb539c11	("usb: dwc3: core: initialize ULPI before trying to get the PHY")
>>>
>>> So looks like this will break ULPI PHY case?
>>>
>>> Where do we initialize ULPI PHY, in dwc3_phy_setup()?
>>>
>>> if so then 541768b08a40 breaks the ULPI PHY case as well, right?
>> 
>> indeed, that commit regressed ULPI PHYs :-(
>> 
>> Seems like it should be more like below:
>> 
>> @@ -754,15 +754,15 @@ static int dwc3_core_init(struct dwc3 *dwc)
>>  			dwc->maximum_speed = USB_SPEED_HIGH;
>>  	}
>>  
>> -	ret = dwc3_core_get_phy(dwc);
>> +	ret = dwc3_phy_setup(dwc);
>
> But can we do a dwc3_phy_setup() without doing the soft reset of the controller first?

as long as clocks are running, we can do that, yes.

>> -	ret = dwc3_core_soft_reset(dwc);
>> +	ret = dwc3_core_get_phy(dwc);
>
> we can get_phy in dwc3_core_init() as it will get called on resume().
> This was the $subject of this patch.

indeed. thanks :-)

-- 
balbi

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