Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Fri, 20 Apr 2018 14:22:51 -0400 (EDT)
From:   Alan Stern <stern@rowland.harvard.edu>
To:     Ravi Chandra Sadineni <ravisadineni@chromium.org>
cc:     gregkh@linuxfoundation.org, <martin.blumenstingl@googlemail.com>,
        <ravisadineni@google.com>, <chunfeng.yun@mediatek.com>,
        <johan@kernel.org>, <arvind.yadav.cs@gmail.com>, <dtor@google.com>,
        <anton.bondarenko.sama@gmail.com>, <f.fainelli@gmail.com>,
        <keescook@chromium.org>, <mathias.nyman@linux.intel.com>,
        <felipe.balbi@linux.intel.com>, <ekorenevsky@gmail.com>,
        <peter.chen@nxp.com>, <joe@perches.com>, <tbroch@google.com>,
        <linux-usb@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <rajatja@google.com>, <bleung@google.com>
Subject: Re: [PATCH V5] USB: Increment wakeup count on remote wakeup.
In-Reply-To: <20180420180821.194380-1-ravisadineni@chromium.org>
Message-ID: <Pine.LNX.4.44L0.1804201422250.1407-100000@iolanthe.rowland.org>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Fri, 20 Apr 2018, Ravi Chandra Sadineni wrote:

> On chromebooks we depend on wakeup count to identify the wakeup source.
> But currently USB devices do not increment the wakeup count when they
> trigger the remote wake. This patch addresses the same.
> 
> Resume condition is reported differently on USB 2.0 and USB 3.0 devices.
> 
> On USB 2.0 devices, a wake capable device, if wake enabled, drives
> resume signal to indicate a remote wake (USB 2.0 spec section 7.1.7.7).
> The upstream facing port then sets C_PORT_SUSPEND bit and reports a
> port change event (USB 2.0 spec section 11.24.2.7.2.3). Thus if a port
> has resumed before driving the resume signal from the host and
> C_PORT_SUSPEND is set, then the device attached to the given port might
> be the reason for the last system wakeup. Increment the wakeup count for
> the same.
> 
> On USB 3.0 devices, a function may signal that it wants to exit from device
> suspend by sending a Function Wake Device Notification to the host (USB3.0
> spec section 8.5.6.4) Thus on receiving the Function Wake, increment the
> wakeup count.
> 
> Signed-off-by: Ravi Chandra Sadineni <ravisadineni@chromium.org>
> ---
> 
> V5: Added the description of changes between different versions of patches.
> V4: Moved the wakeup count increment logic to the existing if which is
> safegaurded by hcd_root_hub_lock spinlock.
> V3: Added a gaurd to check if rh_registered is set before accessing
> root_hub pointer.
> V2: Fixed the build failure error due to uninitialized dev pointer.

Acked-by: Alan Stern <stern@rowland.harvard.edu>