linux-kernel - Re: [PATCH v5 3/3] usb: xhci: remove stop device and ring doorbell in hub control and bus suspend

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Message-ID: <558C15D5.9020802@linux.intel.com>
Date:	Thu, 25 Jun 2015 17:53:09 +0300
From:	Mathias Nyman <mathias.nyman@...ux.intel.com>
To:	Lu Baolu <baolu.lu@...ux.intel.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Mathias Nyman <mathias.nyman@...el.com>,
	Alan Stern <stern@...land.harvard.edu>
CC:	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 3/3] usb: xhci: remove stop device and ring doorbell
 in hub control and bus suspend

On 09.05.2015 04:15, Lu Baolu wrote:
> There is no need to call xhci_stop_device() and xhci_ring_device() in
> hub control and bus suspend functions since all device suspend and
> resume have been notified through device_suspend/device_resume interfaces.

I was looking through this code again before sending it forward, and it occurred to
me that this might be breaking the PORT_SUSPEND and PORT_SET_LINK_STATE port features
for xhci root hub.

In normal use these requests are called by usb core in usb_port_suspend(), which 
also now notifies xhci, which makes sure xhci_stop_device() is called. 

But I don't think there is anything preventing an URB to be sent to the xhci roothub
with a PORT_SUSPEND or PORT_SET_LINK_STATE port feature request. In this case the usb_port_suspend()
is not called, and no notify will stop the device. 

For example hub validation tests might do this

-Mathias

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