From: Dinh Nguyen <dinguyen@kernel.org>
To: Ivid Suvarna <ivid.suvarna@gmail.com>,
Alan Stern <stern@rowland.harvard.edu>
Cc: USB list <linux-usb@vger.kernel.org>,
balbi@kernel.org, gregkh@linuxfoundation.org,
Billy Araujo <billyaraujo@gmail.com>,
johnyoun@synopsys.com,
Felipe Balbi <felipe.balbi@linux.intel.com>,
Kernel development list <linux-kernel@vger.kernel.org>,
Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
Oliver Neukum <oneukum@suse.com>, Johan Hovold <johan@kernel.org>,
Michal Nazarewicz <mina86@mina86.com>,
Vincent Pelletier <plr.vincent@gmail.com>,
Jerry Zhang <zhangjerry@google.com>,
John Keeping <john@metanate.com>,
Krzysztof Opasiak <k.opasiak@samsung.com>,
Abdulhadi Mohamed <abdulahhadi2@gmail.com>,
Matthew Wilcox <willy@linux.intel.com>,
Janusz Dziedzic <januszx.dziedzic@linux.intel.com>
Subject: Re: Suspend to disk with usb connected fails to detect usb(reset) during resume
Date: Thu, 9 Nov 2017 09:17:05 -0600 [thread overview]
Message-ID: <4ff09187-7ee7-78d0-82e2-bb3f763f181f@kernel.org> (raw)
In-Reply-To: <CABXF_ADHJB-Q+Di+iG5SxXcReP-4p0zeQK9ehqD=oH4ad89SEg@mail.gmail.com>
On 11/08/2017 06:29 AM, Ivid Suvarna wrote:
> On Tue, Nov 7, 2017 at 9:19 PM, Alan Stern <stern@rowland.harvard.edu> wrote:
>> On Tue, 7 Nov 2017, Ivid Suvarna wrote:
>>
>>> Hi,
>>>
>>> I am trying to support suspend to disk(hibernate) on Hikey with 4.4
>>> kernel. During suspend, I could see the usb devices getting reset and I
>>> can access them properly. Message can be seen as below:
>>>
>>> usb 1-1: reset high-speed USB device number 2 using dwc2
>>> usb 1-1.2: reset high-speed USB device number 3 using dwc2
>>> usb 1-1.2.4: reset high-speed USB device number 4 using dwc2
>>
>> You might start by asking why the devices need to be reset during
>> suspend. I can't see any reason for doing this.
>>
>> Alan Stern
>>
>
> Yes please. Could you explain as to why the usb needs to reset while
> suspending?
> This scenario is also observed in normal suspend to ram.
>
> And why the USB gets disconnected on resume from hibernation.
> I checked the register dump of usb in /sys/kernel/debug and all
> registers after resume have zero value.
>
Registers with zero value is indicative of a clock not getting turned
on, at least that I have encountered with DWC2 on the SoCFPGA platform.
Dinh
prev parent reply other threads:[~2017-11-09 15:17 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-07 8:04 Ivid Suvarna
2017-11-07 15:49 ` Alan Stern
2017-11-08 12:29 ` Ivid Suvarna
2017-11-08 15:42 ` Alan Stern
2017-11-09 15:17 ` Dinh Nguyen [this message]
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