From mboxrd@z Thu Jan  1 00:00:00 1970
From: greg@kroah.com (Greg KH)
Date: Wed, 18 Jan 2017 18:12:52 +0100
Subject: Downgrade GSM/UMTS module to USB 2.0 Fullspeed
In-Reply-To: <20170118160534.GB11550@graute-opti>
References: <20170118160534.GB11550@graute-opti>
Message-ID: <20170118171252.GA12664@kroah.com>
To: kernelnewbies@lists.kernelnewbies.org
List-Id: kernelnewbies.lists.kernelnewbies.org

On Wed, Jan 18, 2017 at 05:05:34PM +0100, Oliver Graute wrote:
> Hello list,
> 
> i'am using a GSM/UMTS Module on a PCB which is connected with USB 2.0
> Hi-Speed to my imx6ul CPU. To reduce our Electromagnetic compatibility
> and to make my hardware colleges happy again I want to downgrade to USB
> Full Speed.
> 
> How can I tell the Linux Kernel to Do so?

You can't.  It's up to the device to tell the host what "speed" it is
running at.  See the USB spec for all of the crazy details.

I suggest you modify the firmware of your modem to do this, that's the
only way it is going to work (note, your device needs to be able to
support full speed, it might not be able to do that.)

good luck!

greg k-h