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From: Alan Stern <stern@rowland.harvard.edu>
To: Roger Quadros <rogerq@ti.com>
Cc: Zeng Tao <prime.zeng@hisilicon.com>, <gregkh@linuxfoundation.org>,
	<mathias.nyman@linux.intel.com>, <drinkcat@chromium.org>,
	<felipe.balbi@linux.intel.com>, <drake@endlessm.com>,
	<mike.looijmans@topic.nl>, <joe@perches.com>,
	<linux-usb@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] usb: hub: try old enumeration scheme first for high speed devices
Date: Fri, 10 Aug 2018 10:19:30 -0400 (EDT)	[thread overview]
Message-ID: <Pine.LNX.4.44L0.1808101017050.1425-100000@iolanthe.rowland.org> (raw)
In-Reply-To: <a29afa26-22b4-3188-f9ee-993e44df7703@ti.com>

On Fri, 10 Aug 2018, Roger Quadros wrote:

> Hi,
> 
> On 10/08/18 18:01, Zeng Tao wrote:
> > The new scheme is required just to support legacy low and full-speed
> > devices. For high speed devices, it will slower the enumeration speed.
> > So in this patch we try the "old" enumeration scheme first for high speed
> > devices.
> 
> How slow does it get? Is it significant?
> Do we risk breaking existing HS devices that work? I don't think we can
> be sure till we run this through testing.

Indeed.  I am extremely skeptical about a patch like this, unless
somebody can show that Windows uses the "old" scheme for high-speed 
devices.

Alan Stern


  reply	other threads:[~2018-08-10 14:19 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-10 15:01 [PATCH] usb: hub: try old enumeration scheme first for high speed devices Zeng Tao
2018-08-10 10:50 ` Roger Quadros
2018-08-10 14:19   ` Alan Stern [this message]
2018-08-14  7:35     ` Zengtao (B)
2018-08-14 14:39       ` Alan Stern
2018-08-16  6:21         ` Zengtao (B)
2018-08-16  7:16           ` Roger Quadros
2018-08-16 10:59             ` Zengtao (B)
2018-08-16 11:13               ` Roger Quadros
2018-08-17  2:15                 ` Zengtao (B)
2018-08-14  7:33   ` Zengtao (B)
2018-08-16  7:31     ` Roger Quadros
2018-09-28 11:27 Zeng Tao

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