linux-kernel - Re: [RESEND PATCH 1/3] usb: dwc3: Don't reinitialize core during host bus-suspend/resume

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Date:   Wed, 10 Jan 2018 14:59:35 +0200
From:   Roger Quadros <rogerq@...com>
To:     Felipe Balbi <balbi@...nel.org>,
        Manu Gautam <mgautam@...eaurora.org>
CC:     <linux-arm-msm@...r.kernel.org>, <linux-usb@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        open list <linux-kernel@...r.kernel.org>,
        linux-omap <linux-omap@...r.kernel.org>
Subject: Re: [RESEND PATCH 1/3] usb: dwc3: Don't reinitialize core during host
 bus-suspend/resume

On 10/01/18 14:57, Felipe Balbi wrote:
> 
> Hi,
> 
> Roger Quadros <rogerq@...com> writes:
>> Hi Manu,
>>
>> On 27/09/17 14:19, Manu Gautam wrote:
>>> Driver powers-off PHYs and reinitializes DWC3 core and gadget on
>>> resume. While this works fine for gadget mode but in host
>>> mode there is not re-initialization of host stack. Also, resetting
>>> bus as part of bus_suspend/resume is not correct which could affect
>>> (or disconnect) connected devices.
>>> Fix this by not reinitializing core on suspend/resume in host mode
>>> for HOST only and OTG/drd configurations.
>>>
>>
>> All this seems correct but we (TI) were relying on dwc3_core_exit() to be called
>> during dwc3_suspend() to have the lowest power state for our platforms.
>>
>> After this patch, DWC3 controller and PHYs won't be turned off thus
>> preventing our platform from reaching low power levels.
>>
>> So this is a regression for us (TI) in v4.15-rc.
>>
>> Felipe, do you agree?
>>
>> If yes I can send a patch which fixes the regression
>> and also makes USB host work after suspend/resume.
> 
> A power consumption regression is still a regression. But it's super
> late in the -rc cycle, I think we need to get this merged after 4.16-rc1
> and make sure to Cc stable.
> 
> Should be more than enough time to review and test patches.
> 

Fine with me. 

-- 
cheers,
-roger

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