Re: [PATCH v3 1/2] usb: host: ehci-tegra: Grab the correct UTMI pads reset

From: Greg Kroah-Hartman
Date: Wed May 04 2016 - 10:57:15 EST

On Wed, May 04, 2016 at 04:39:59PM +0200, Thierry Reding wrote:
> From: Thierry Reding <treding@xxxxxxxxxx>
> There are three EHCI controllers on Tegra SoCs, each with its own reset
> line. However, the first controller contains a set of UTMI configuration
> registers that are shared with its siblings. These registers will only
> be reset as part of the first controller's reset. For proper operation
> it must be ensured that the UTMI configuration registers are reset
> before any of the EHCI controllers are enabled, irrespective of the
> probe order.
> Commit a47cc24cd1e5 ("USB: EHCI: tegra: Fix probe order issue leading to
> broken USB") introduced code that ensures the first controller is always
> reset before setting up any of the controllers, and is never again reset
> afterwards.
> This code, however, grabs the wrong reset. Each EHCI controller has two
> reset controls attached: 1) the USB controller reset and 2) the UTMI
> pads reset (really the first controller's reset). In order to reset the
> UTMI pads registers the code must grab the second reset, but instead it
> grabbing the first.
> Signed-off-by: Thierry Reding <treding@xxxxxxxxxx>

Any reason you don't want this backported to stable kernels?