From: Alan Stern <stern@rowland.harvard.edu>
To: Matthias Kaehlcke <mka@chromium.org>
Cc: Peter Chen <peter.chen@nxp.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Rob Herring <robh+dt@kernel.org>,
Frank Rowand <frowand.list@gmail.com>,
Krzysztof Kozlowski <krzk@kernel.org>,
Bastien Nocera <hadess@hadess.net>,
Ravi Chandra Sadineni <ravisadineni@chromium.org>,
"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
Stephen Boyd <swboyd@chromium.org>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
Douglas Anderson <dianders@chromium.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Alexander A. Klimov" <grandmaster@al2klimov.de>,
Masahiro Yamada <masahiroy@kernel.org>
Subject: Re: [PATCH 2/2] USB: misc: Add onboard_usb_hub driver
Date: Tue, 15 Sep 2020 22:14:21 -0400 [thread overview]
Message-ID: <20200916021421.GA1024554@rowland.harvard.edu> (raw)
In-Reply-To: <20200915230345.GF2771744@google.com>
On Tue, Sep 15, 2020 at 04:03:45PM -0700, Matthias Kaehlcke wrote:
> Hi Peter,
>
> On Tue, Sep 15, 2020 at 07:05:38AM +0000, Peter Chen wrote:
> > Whether or not it is a wakeup_source, it could get through its or its children's
> > /sys/../power/wakeup value, you have already used usb_wakeup_enabled_descendants
> > to know it.
>
> I conceptually agree, but in practice there are some conflicting details:
>
> wakeup for the hubs on my system is by default disabled, yet USB wakeup works
> regardless, so the flag doesn't really provide useful information. I guess we
> could still use it if there is no better way, but it doesn't seem ideal.
The wakeup setting for USB hubs affects only the following events: port
connect, port disconnect, and port overcurrent. It does not refer to
forwarding wakeup requests from downstream USB devices; that is always
enabled. So maybe your wakeup flag really is accurate and you didn't
realize it.
> Similar for udev->bus->controller, according to sysfs it doesn't even have wakeup
> support. Please let me know if there is a reliable way to check if wakeup is
> enabled on the controller of a device.
The host controller's sysfs wakeup setting should always be correct. If
it isn't, that indicates there is a bug in the host controller driver or
the corresponding platform-specific code. What driver does your system
use?
Alan Stern
next prev parent reply other threads:[~2020-09-16 2:14 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-14 18:27 [PATCH 1/2] dt-bindings: usb: Add binding for onboard USB hubs Matthias Kaehlcke
2020-09-14 18:27 ` [PATCH 2/2] USB: misc: Add onboard_usb_hub driver Matthias Kaehlcke
2020-09-14 19:52 ` Matthias Kaehlcke
2020-09-14 20:14 ` Alan Stern
2020-09-14 21:14 ` Matthias Kaehlcke
2020-09-15 2:55 ` Peter Chen
2020-09-15 5:02 ` Matthias Kaehlcke
2020-09-15 7:05 ` Peter Chen
2020-09-15 23:03 ` Matthias Kaehlcke
2020-09-16 2:14 ` Alan Stern [this message]
2020-09-16 19:27 ` Matthias Kaehlcke
2020-09-16 8:19 ` Peter Chen
2020-09-16 19:16 ` Matthias Kaehlcke
2020-09-17 0:27 ` Peter Chen
2020-09-17 0:47 ` Matthias Kaehlcke
2020-09-17 1:24 ` Peter Chen
2020-09-17 15:54 ` Matthias Kaehlcke
2020-09-15 14:21 ` [PATCH 1/2] dt-bindings: usb: Add binding for onboard USB hubs Rob Herring
2020-09-16 0:00 ` Matthias Kaehlcke
2020-09-18 16:05 ` Rob Herring
2020-09-22 23:39 ` Matthias Kaehlcke
2020-09-15 14:21 ` Rob Herring
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