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

[Greg Kroah-Hartman]

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.

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

thanks,

greg k-h