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

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Message-ID: <876089zxau.fsf@linux.intel.com>
Date:   Wed, 10 Jan 2018 14:57:13 +0200
From:   Felipe Balbi <balbi@...nel.org>
To:     Roger Quadros <rogerq@...com>, 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


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.

-- 
balbi

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