Re: [PATCH] USB:fix USB3 devices behind USB3 hubs not resuming at hibernate thaw

[Xing Zhengjun]

On 3/22/2018 8:03 PM, Greg KH wrote:
> On Wed, Mar 21, 2018 at 01:29:42PM +0800, Zhengjun Xing wrote:
> > USB3 hubs don't support global suspend.
> >
> > USB3 specification 10.10, Enhanced SuperSpeed hubs only support selective
> > suspend and resume, they do not support global suspend/resume where the
> > hub downstream facing ports states are not affected.
> >
> > When system enters hibernation it first enters freeze process where only
> > the root hub enters suspend, usb_port_suspend() is not called for other
> > devices, and suspend status flags are not set for them. Other devices are
> > expected to suspend globally. Some external USB3 hubs will suspend the
> > downstream facing port at global suspend. These devices won't be resumed
> > at thaw as the suspend status flag is not set.
> >
> > A USB3 removable hard disk connected through a USB3 hub that won't resume
> > at thaw will fail to synchronize SCSI cache, return âcmd cmplt err -71â
> > error, and needs a 60 seconds timeout which causing system hang for 60s
> > before the USB host reset the port for the USB3 removable hard disk to
> > recover.
> >
> > Fix this by always calling usb_port_suspend() during freeze for USB3
> > devices.
> This should go to the stable trees as well, right?
>
> greg k-h
 Yes. It should go to the stable trees.