Re: [PATCH v2 1/1] xhci: add USB2 test mode support

[Mathias Nyman]

On 08.02.2017 15:44, Alexander Stein wrote:
> This patch adds support for USB2 test mode (Test_J, Test_K,
> Test_SE0_NAK and Test_Packet) per XHCI spec 4.19.6.
>
> USB2 test mode is a required hardware feature for system integrators
> validating their hardware according to USB spec, regarding signal
> strength and stuff. It is purely a hardware test feature.
>
> Usually you need an oscilloscope and have to enable those test modes on
> the hardware. This will send some specific test patterns on D+/D-. There
> is no report available (in Linux itself) as it is purely externally
> visible. Regular USB usage is not possible at that time.
> Anyone (well access to e.g. /dev/bus/usb/001/001 provided) can use it by
> sending appropriate USB_PORT_FEAT_TEST requests to the hub.
> The same feature for ehci based hosts is already available at
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/drivers/usb/host/ehci-hub.c#n1267
>
> Signed-off-by: "Wang, Yu" <yu.y.wang@xxxxxxxxx>
> Signed-off-by: "Li, Guanglei" <guangleix.li@xxxxxxxxx>
> Signed-off-by: "Wu, Hao" <hao.wu@xxxxxxxxx>
> Signed-off-by: Alexander Stein <alexander.stein@xxxxxxxxxxxxxxxxxxxxx>
> ---

I think there's a reworked series of this feature already posted at:

http://marc.info/?l=linux-usb&m=148050258916147&w=2

But this change log is now better
I was thinking about adding that to 4.12

-Mathias