From: Felipe Balbi <balbi@ti.com>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Douglas Anderson <dianders@chromium.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
John Youn <johnyoun@synopsys.com>, Felipe Balbi <balbi@ti.com>,
<linux-usb@vger.kernel.org>, Chris Zhong <zyw@rock-chips.com>,
Heiko Stuebner <heiko@sntech.de>,
Julius Werner <jwerner@chromium.org>,
Andrew Bresticker <abrestic@chromium.org>,
Alexandru Stan <amstan@chromium.org>, <lyz@rock-chips.com>,
<linux-rockchip@lists.infradead.org>,
<linux-kernel@vger.kernel.org>
Subject: Re: [REPOST PATCH 3/3] USB: dwc2: Don't turn off the usbphy in suspend if wakeup is enabled
Date: Mon, 6 Jul 2015 14:02:12 -0500 [thread overview]
Message-ID: <20150706190212.GN20779@saruman.tx.rr.com> (raw)
In-Reply-To: <Pine.LNX.4.44L0.1507061450190.1860-100000@iolanthe.rowland.org>
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On Mon, Jul 06, 2015 at 02:58:16PM -0400, Alan Stern wrote:
> On Mon, 6 Jul 2015, Douglas Anderson wrote:
>
> > If the 'snps,need-phy-for-wake' is set in the device tree then:
> >
> > - We know that we can wakeup, so call device_set_wakeup_capable().
> > The USB core will use this knowledge to enable wakeup by default.
> > - We know that we should keep the PHY on during suspend if something
> > on our root hub needs remote wakeup. This requires the patch (USB:
> > Export usb_wakeup_enabled_descendants()). Note that we don't keep
> > the PHY on at suspend time if it's not needed because it would be a
> > power draw.
>
> You know, this is the first time I've run across this optimization.
>
> In principle it applies to any USB host controller, not just to PHYs.
> There's no reason to enable wakeup for a controller if none of the
> attached devices can issue a wakeup request.
>
> I don't know if implementing this in other HCDs would save any power.
> Any ideas?
most likely it would. Enabling wakeup usually boils down to keeping a
tiny part of the controller (or PHY) powered up. Sometimes that lies in
an always-on power domain, so there would be no difference.
cheers
--
balbi
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WARNING: multiple messages have this Message-ID (diff)
From: Felipe Balbi <balbi-l0cyMroinI0@public.gmane.org>
To: Alan Stern <stern-nwvwT67g6+6dFdvTe/nMLpVzexx5G7lz@public.gmane.org>
Cc: Heiko Stuebner <heiko-4mtYJXux2i+zQB+pC5nmwQ@public.gmane.org>,
linux-rockchip-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org,
John Youn <johnyoun-HKixBCOQz3hWk0Htik3J/w@public.gmane.org>,
Greg Kroah-Hartman
<gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org>,
linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Douglas Anderson
<dianders-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>,
Felipe Balbi <balbi-l0cyMroinI0@public.gmane.org>,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Andrew Bresticker
<abrestic-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>,
lyz-TNX95d0MmH7DzftRWevZcw@public.gmane.org,
Chris Zhong <zyw-TNX95d0MmH7DzftRWevZcw@public.gmane.org>,
Julius Werner <jwerner-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>,
Alexandru Stan <amstan-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>
Subject: Re: [REPOST PATCH 3/3] USB: dwc2: Don't turn off the usbphy in suspend if wakeup is enabled
Date: Mon, 6 Jul 2015 14:02:12 -0500 [thread overview]
Message-ID: <20150706190212.GN20779@saruman.tx.rr.com> (raw)
In-Reply-To: <Pine.LNX.4.44L0.1507061450190.1860-100000-IYeN2dnnYyZXsRXLowluHWD2FQJk+8+b@public.gmane.org>
[-- Attachment #1.1: Type: text/plain, Size: 1246 bytes --]
On Mon, Jul 06, 2015 at 02:58:16PM -0400, Alan Stern wrote:
> On Mon, 6 Jul 2015, Douglas Anderson wrote:
>
> > If the 'snps,need-phy-for-wake' is set in the device tree then:
> >
> > - We know that we can wakeup, so call device_set_wakeup_capable().
> > The USB core will use this knowledge to enable wakeup by default.
> > - We know that we should keep the PHY on during suspend if something
> > on our root hub needs remote wakeup. This requires the patch (USB:
> > Export usb_wakeup_enabled_descendants()). Note that we don't keep
> > the PHY on at suspend time if it's not needed because it would be a
> > power draw.
>
> You know, this is the first time I've run across this optimization.
>
> In principle it applies to any USB host controller, not just to PHYs.
> There's no reason to enable wakeup for a controller if none of the
> attached devices can issue a wakeup request.
>
> I don't know if implementing this in other HCDs would save any power.
> Any ideas?
most likely it would. Enabling wakeup usually boils down to keeping a
tiny part of the controller (or PHY) powered up. Sometimes that lies in
an always-on power domain, so there would be no difference.
cheers
--
balbi
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next prev parent reply other threads:[~2015-07-06 19:02 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-06 18:27 [REPOST PATCH 0/3] dwc2 patches to allow wakeup on Rockchip rk3288 Douglas Anderson
2015-07-06 18:27 ` Douglas Anderson
2015-07-06 18:27 ` [REPOST PATCH 1/3] USB: Export usb_wakeup_enabled_descendants() Douglas Anderson
2015-07-06 18:27 ` Douglas Anderson
2015-07-06 18:27 ` [REPOST PATCH 2/3] Documentation: dt-bindings: Add snps,need-phy-for-wake for dwc2 USB Douglas Anderson
2015-07-06 18:27 ` Douglas Anderson
2015-07-06 18:27 ` [REPOST PATCH 3/3] USB: dwc2: Don't turn off the usbphy in suspend if wakeup is enabled Douglas Anderson
2015-07-06 18:27 ` Douglas Anderson
2015-07-06 18:34 ` Felipe Balbi
2015-07-06 18:34 ` Felipe Balbi
2015-07-06 19:32 ` Doug Anderson
2015-07-06 19:32 ` Doug Anderson
2015-07-06 19:35 ` Felipe Balbi
2015-07-06 19:35 ` Felipe Balbi
2015-07-06 18:58 ` Alan Stern
2015-07-06 18:58 ` Alan Stern
2015-07-06 19:02 ` Felipe Balbi [this message]
2015-07-06 19:02 ` Felipe Balbi
2015-07-06 19:39 ` Doug Anderson
2015-07-06 19:39 ` Doug Anderson
2015-07-07 14:28 ` Alan Stern
2015-07-07 14:28 ` Alan Stern
2015-07-08 0:06 ` Julius Werner
2015-07-08 0:06 ` Julius Werner
2015-07-08 15:01 ` Alan Stern
2015-07-08 19:41 ` Julius Werner
2015-07-08 19:41 ` Julius Werner
2015-07-08 19:58 ` Alan Stern
2015-07-08 19:58 ` Alan Stern
2015-10-21 16:23 ` [REPOST PATCH 0/3] dwc2 patches to allow wakeup on Rockchip rk3288 Doug Anderson
2015-10-21 16:23 ` Doug Anderson
2015-10-27 2:05 ` John Youn
2015-10-27 2:05 ` John Youn
2015-10-31 0:01 ` Doug Anderson
2015-10-31 0:01 ` Doug Anderson
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