Re: [PATCH stable 5.4] usb: host: xhci-plat: add wakeup entry at sysfs

[Florian Fainelli]

On 2/2/23 23:58, Greg Kroah-Hartman wrote:
> On Wed, Feb 01, 2023 at 03:19:08PM -0800, Florian Fainelli wrote:
> > On 2/1/23 10:16, Greg Kroah-Hartman wrote:
> > > On Wed, Feb 01, 2023 at 09:44:04AM -0800, Florian Fainelli wrote:
> > > > From: Peter Chen <peter.chen@xxxxxxx>
> > > >
> > > > commit  4bb4fc0dbfa23acab9b762949b91ffd52106fe4b upstream
> > > >
> > > > With this change, there will be a wakeup entry at /sys/../power/wakeup,
> > > > and the user could use this entry to choose whether enable xhci wakeup
> > > > features (wake up system from suspend) or not.
> > > >
> > > > Tested-by: Matthias Kaehlcke <mka@xxxxxxxxxxxx>
> > > > Reviewed-by: Matthias Kaehlcke <mka@xxxxxxxxxxxx>
> > > > Signed-off-by: Peter Chen <peter.chen@xxxxxxx>
> > > > Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
> > > > Link: https://lore.kernel.org/r/20200918131752.16488-6-mathias.nyman@xxxxxxxxxxxxxxx
> > > > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > > > Signed-off-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
> > > > ---
> > > >    drivers/usb/host/xhci-plat.c | 2 +-
> > > >    1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > Why is this new feature needed on these older kernels?  What does it fix
> > > that is broken?
> >
> > It fixes the inability to make the XHCI controller a wake-up device since
> > there is no /sys/*/*xhci/power/wakeup sysfs entry to manipulate unless this
> > patch is applied.
>
> But that is a new feature, not a bugfix.

Support for wake-up was already there in the xhci driver, just there was 
no way to activate it from user-space, that seems like a fix to me.

> What systems need this for these older kernels that will actually update
> to them in order to pick up this change?

Some NXP systems required that, and all of our ARCH_BRCMSTB SoCs also 
have that capability, I see you applied those patches, thanks!
--
Florian