From: Ramneek Mehresh <ramneek.mehresh@freescale.com>
To: Alan Stern <stern@rowland.harvard.edu>
CC: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "balbi@ti.com" <balbi@ti.com>,
        "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
        "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
        Li Leo <LeoLi@freescale.com>
Subject: RE: [PATCH 3/8][v2]usb:fsl:otg: Add support to add/remove usb host
 driver
Thread-Topic: [PATCH 3/8][v2]usb:fsl:otg: Add support to add/remove usb host
 driver
Thread-Index: AQHQvvR6ysWYVpVYJU+lfkTENAcEOp4BIr6AgAO57aCAAJuEgIAADjNg
Date: Mon, 10 Aug 2015 15:35:54 +0000
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> -----Original Message-----
> From: Alan Stern [mailto:stern@rowland.harvard.edu]
> Sent: Monday, August 10, 2015 8:14 PM
> To: Mehresh Ramneek-B31383
> Cc: linux-kernel@vger.kernel.org; balbi@ti.com;
> gregkh@linuxfoundation.org; linux-usb@vger.kernel.org; Li Yang-Leo-R58472
> Subject: RE: [PATCH 3/8][v2]usb:fsl:otg: Add support to add/remove usb
> host driver
> 
> On Mon, 10 Aug 2015, Ramneek Mehresh wrote:
> 
> > > Also, what is the reason for calling usb_hcd_resume_root_hub()?  It
> won't
> > > do anything, because it will run before the scheduled work, so there
> won't
> > > be a root hub for it to resume.
> > >
> > Well, you're right...it's not a surety that usb_hcd_resume_root_hub() will
> run after
> > scheduled work...i'll move it inside do_change_hcd() after usb_add_hcd().
> Thanks.
> 
> You're missing the point.  There's no reason ever to call
> usb_hcd_resume_root_hub() immediately after usb_add_hcd().  The hub
> driver does everything necessary when the root hub is registered.
> Resuming it (if it is suspended at that point) won't accomplish
> anything because all the important work has just been done.
> 
> Now, if you _weren't_ calling usb_add_hcd() (for example if host.is_otg
> were 0) then it might make sense to call usb_hcd_resume_root_hub() --
> although I don't see why you would need to.
> 
> Alan Stern
Understood...let me check this once again. Thanks.

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