RE: [PATCH 1/1] usb: lpm: add boot flag to disable lpm

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The devices support LPM and are USB3.0 certified, and they work fine in
Windows using the same Intel 8/9/10 Series USB host controllers, along
with Renesas and Fresco controllers. On Linux the devices either seize
up or slow down dramatically ever since LPM support was enabled.

I could always just build a custom kernel ".deb" package for customers
for now, as some of them are migrating from Ubuntu 14.04.3 LTS (kernel
3.19.0-51) to Ubuntu 14.04.4 LTS (kernel 4.2.x) or Ubuntu 16.04 LTS
(kernel 4.4.x), but I'd like to avoid that solution. Ideally, disabling
LPM on a per-device basis would be better than the solution I proposed,
but I'm not familiar enough with the usbcore code to implement such a
feature at this time. I'd also prefer customers go with an official
kernel release and just add a custom boot parameter.

============================================================
Matthew Giassa, MASc, BASc, EIT
Security and Embedded Systems Specialist
linkedin: https://ca.linkedin.com/in/giassa
e-mail:   matthew@xxxxxxxxxx
website:  www.giassa.net

> -------- Original Message --------
> Subject: Re: [PATCH 1/1] usb: lpm: add boot flag to disable lpm
> From: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>
> Date: Wed, April 13, 2016 3:11 pm
> To: Matthew Giassa <matthew@xxxxxxxxxx>
> Cc: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>,
> linux-usb@xxxxxxxxxxxxxxx
> 
> 
> On Wed, Apr 13, 2016 at 02:37:35PM -0700, Matthew Giassa wrote:
> > Thank you for the feedback Greg. This is my first attempt to submit a
> > kernel patch.
> > 
> > Is there a better approach to this? The only other option at my disposal
> > is to add about 200 products to the quirks.c file, and routinely update
> > that list as new products are released. I need to implement some means
> > of disabling LPM, ideally on a per-device basis.
> 
> Why are these devices say they support LPM yet they do not?
> 
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