lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Mon, 29 Apr 2019 22:25:52 -0700
From:   Doug Anderson <dianders@...omium.org>
To:     Rob Herring <robh@...nel.org>
Cc:     Minas Harutyunyan <hminas@...opsys.com>,
        Felipe Balbi <felipe.balbi@...ux.intel.com>,
        Heiko Stübner <heiko@...ech.de>,
        Alan Stern <stern@...land.harvard.edu>,
        Artur Petrosyan <Arthur.Petrosyan@...opsys.com>,
        Alexandru M Stan <amstan@...omium.org>,
        "open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
        William Wu <william.wu@...k-chips.com>,
        linux-usb@...r.kernel.org, Stefan Wahren <stefan.wahren@...e.com>,
        Randy Li <ayaka@...lik.info>, Chris <zyw@...k-chips.com>,
        Matthias Kaehlcke <mka@...omium.org>,
        Ryan Case <ryandcase@...omium.org>,
        Amelie Delaunay <amelie.delaunay@...com>,
        Julius Werner <jwerner@...omium.org>,
        Dinh Nguyen <dinguyen@...nsource.altera.com>,
        Elaine Zhang <zhangqing@...k-chips.com>,
        devicetree@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH v2 3/5] Documentation: dt-bindings: Add
 snps,need-phy-for-wake for dwc2 USB

Hi,

On Mon, Apr 29, 2019 at 6:23 PM Rob Herring <robh@...nel.org> wrote:
>
> On Wed, Apr 17, 2019 at 05:13:54PM -0700, Douglas Anderson wrote:
> > Some SoCs with a dwc2 USB controller may need to keep the PHY on to
> > support remote wakeup.  Allow specifying this as a device tree
> > property.
> >
> > Signed-off-by: Douglas Anderson <dianders@...omium.org>
> > ---
> > For relevant prior discussion on this patch, see:
> >
> > https://lkml.kernel.org/r/1435017144-2971-3-git-send-email-dianders@chromium.org
> >
> > I didn't make any changes from the prior version since I never found
> > out what Rob thought of my previous arguments.  If folks want a
> > change, perhaps they could choose from these options:
> >
> > 1. Assume that all dwc2 hosts would like to keep their PHY on for
> >    suspend if there's a USB wakeup enabled, thus we totally drop this
> >    binding.  This doesn't seem super great to me since I'd bet that
> >    many devices that use dwc2 weren't designed for USB wakeup (they
> >    may not keep enough clocks or rails on) so we might be wasting
> >    power for nothing.
>
> 1b. Use SoC specific compatible strings to enable/disable remote
> wake-up. We can debate what the default is I guess.

Unfortunately it's more than just SoC.  While you need the SoC to be
able to support this type of wakeup, you also need the board design,
firmware design, regulator design, etc.  ...so I don't think we can
just use the SoC specific compatible string.

In fact, while testing this I found that USB wakeup was totally broken
unless I enabled "deep suspend" mode on my system.  Something about
the clocks / wakeup sources in the shallow suspend totally blocked it
and I couldn't figure out what.

...so I believe it really needs to be something where someone has
said: I tested it out on this board and everything is setup properly
to support USB wakeup.


> > 2. Rename this property to "snps,wakeup-from-suspend-with-phy" to make
> >    it more obvious that this property is intended both to document
> >    that wakeup from suspend is possible and that we need the PHY for
> >    said wakeup.
> > 3. Rename this property to "snps,can-wakeup-from-suspend" and assume
> >    it's implicit that if we can wakeup from suspend that we need to
> >    keep the PHY on.  If/when someone shows that a device exists using
> >    dwc2 where we can wakeup from suspend without the PHY they can add
> >    a new property.
> >
> > Changes in v2: None
> >
> >  Documentation/devicetree/bindings/usb/dwc2.txt | 3 +++
> >  1 file changed, 3 insertions(+)

Powered by blists - more mailing lists