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:   Mon, 7 Jan 2019 17:16:20 +0100
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Kai-Heng Feng <kai.heng.feng@canonical.com>
Cc:     linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4] USB: Don't enable LPM if it's already enabled
Message-ID: <20190107161620.GB2292@kroah.com>
References: <20181203102643.22690-1-kai.heng.feng@canonical.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20181203102643.22690-1-kai.heng.feng@canonical.com>
User-Agent: Mutt/1.11.1 (2018-12-01)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Mon, Dec 03, 2018 at 06:26:43PM +0800, Kai-Heng Feng wrote:
> USB Bluetooth controller QCA ROME (0cf3:e007) sometimes stops working
> after S3:
> [ 165.110742] Bluetooth: hci0: using NVM file: qca/nvm_usb_00000302.bin
> [ 168.432065] Bluetooth: hci0: Failed to send body at 4 of 1953 (-110)
> 
> After some experiments, I found that disabling LPM can workaround the
> issue.
> 
> On some platforms, the USB power is cut during S3, so the driver uses
> reset-resume to resume the device. During port resume, LPM gets enabled
> twice, by usb_reset_and_verify_device() and usb_port_resume().
> 
> So let's enable LPM for just once, as this solves the issue for the
> device in question.
> 
> Also consolidate USB2 LPM functions to usb_enable_usb2_hardware_lpm()
> and usb_disable_usb2_hardware_lpm().
> 
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>

What kernel patch does this one "fix"?  Adding a "Fixes:" tag would be
good to try to figure out how far back in the kernel releases this
should be backported.

thanks,

greg k-h