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

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Date:   Mon, 15 Jan 2018 17:40:10 +0200
From:   Roger Quadros <rogerq@...com>
To:     Manu Gautam <mgautam@...eaurora.org>,
        Felipe Balbi <balbi@...nel.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

Hi Manu,

On 11/01/18 03:41, Manu Gautam wrote:
> Hi,
> 
> 
> On 1/10/2018 6:18 PM, Roger Quadros wrote:
>> 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.
>>
> 
> I think it will be better to separate runtime_suspend and pm_suspend handling for
> host mode in dwc3. Powering offf/on PHYs and dwc3_core_exit/init across system
> suspend-resume should be ok but doing that for runtime suspend-resume is not
> correct.
> Let me know if that sounds ok, I can provide a patch for same instead of
> reverting this which affects runtime PM with dwc3 host.
> Also, we need to consider dwc3 in Host mode with dr_mode as DRD/OTG similar to
> dr_mode as HOST.
> 
> 

Are you going to provide a patch for this any time soon?

FYI, suspend/resume is broken on DRA7x with Dual-role while in host mode.

-- 
cheers,
-roger

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki