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From:   Minas Harutyunyan <Minas.Harutyunyan@synopsys.com>
To:     Stefan Wahren <stefan.wahren@i2se.com>,
        Minas Harutyunyan <Minas.Harutyunyan@synopsys.com>
CC:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
        Doug Anderson <dianders@chromium.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH RFC] usb: dwc2: power off during shutdown
Thread-Topic: [PATCH RFC] usb: dwc2: power off during shutdown
Thread-Index: AQHUQdnrerw4ENQnyUeZCj/DHLE7ag==
Date:   Thu, 6 Sep 2018 06:33:07 +0000
Message-ID: <410670D7E743164D87FA6160E7907A56013A7646E0@am04wembxa.internal.synopsys.com>
References: <1535795683-3788-1-git-send-email-stefan.wahren@i2se.com>
 <410670D7E743164D87FA6160E7907A56013A761B2B@am04wembxa.internal.synopsys.com>
 <470783016.30183.1536172949193@email.1und1.de>
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Hi Stefan,=0A=
=0A=
On 9/5/2018 10:42 PM, Stefan Wahren wrote:=0A=
> Hi Minas,=0A=
> =0A=
>> Minas Harutyunyan <Minas.Harutyunyan@synopsys.com> hat am 5. September 2=
018 um 10:37 geschrieben:=0A=
>>=0A=
>>=0A=
>> Hi Stefan,=0A=
>>=0A=
>> On 9/1/2018 1:55 PM, Stefan Wahren wrote:=0A=
>>> Currently USB consumes a lot of power after shutting down a Raspberry P=
i 3=0A=
>>> (example setup with Ethernet and a keyboard connected). So power off=0A=
>>> USB on shutdown.=0A=
>>>=0A=
>>> Measured on Raspberry Pi 3B with 4.19rc1/multi_v7_defconfig (HDMI, Ethe=
rnet=0A=
>>> and a keyboard connected)=0A=
>>>=0A=
>>> Before patch: 2.450 W=0A=
>>> After patch:  2.090 W=0A=
>>>=0A=
>>=0A=
>> Could you please elaborate. Power measurements done after shutdown?=0A=
> =0A=
> I did the following:=0A=
> =0A=
> sudo halt=0A=
> wait until "System halted" appears on the screen=0A=
> "measured" the current value displayed on my PSU=0A=
> =0A=
> You are right that not the same as poweroff. But in even in poweroff the =
board consumes 0.6 W, but in this case USB is powered down.=0A=
> =0A=
>> Why=0A=
>> your setup continue consume power after shutdown?=0A=
> =0A=
> The BCM2835 SoC has a GPU and a ARM core. Linux is running only on the AR=
M core. The GPU is usually running a close source firmware, which is starte=
d at first during boot und runs all the time.=0A=
> =0A=
>> Maybe its=0A=
>> sleep/hibernation mode?=0A=
> =0A=
> There isn't much implementation of power management for BCM2835 yet. So i=
 wanted to start with USB.=0A=
> Even for sleep/hibernation the consumption is much too high. Because the =
system consumes in idle 1.6 W.=0A=
> =0A=
>>=0A=
>> dwc2 core in your platform which type of power optimization supports:=0A=
>> partial power down, hibernation or extended hibernation? Please provide=
=0A=
>> me GHWCFG4 register value of your core.=0A=
> =0A=
> AFAIK all RPis use the same USB IP core:=0A=
> =0A=
> GHWCFG4 =3D 0x1ff00020=0A=
=0A=
Ok, your core doesn't support any power optimization mode.=0A=
=0A=
=0A=
> =0A=
> Stefan=0A=
> =0A=
=0A=
1. Could you please explain what is real/physical cause of power saving =0A=
after your patch: VBUS off, PHY clock stop or any other?=0A=
2. Can USB detect remote wake-up signaling from connected =0A=
keyboard/ethernet before and after your patch?=0A=
=0A=
Thanks,=0A=
Minas=0A=