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Date: Thu, 26 Apr 2018 17:32:06 +0200
From: Greg KH <greg@kroah.com>
To: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: stable@vger.kernel.org, Hans de Goede <hdegoede@redhat.com>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Linus Walleij <linus.walleij@linaro.org>,
        Benjamin Tissoires <btissoir@redhat.com>
Subject: Re: Revert f5a26acf0162 ("pinctrl: intel: Initialize GPIO properly
 when used through irqchip") from stable trees
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 <20180426132427.GA20051@kroah.com>
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On Thu, Apr 26, 2018 at 04:36:23PM +0300, Mika Westerberg wrote:
> On Thu, Apr 26, 2018 at 03:24:27PM +0200, Greg KH wrote:
> > On Thu, Apr 26, 2018 at 03:53:02PM +0300, Mika Westerberg wrote:
> > > Hi,
> > > 
> > > It seems that commit f5a26acf0162 ("pinctrl: intel: Initialize GPIO
> > > properly when used through irqchip") can cause problems on some Skylake
> > > systems with Sunrisepoint PCH-H. Namely on certain systems it may turn
> > > the backlight PWM pin from native mode to GPIO which makes the screen
> > > blank during boot.
> > > 
> > > There is more information here:
> > > 
> > >   https://bugzilla.redhat.com/show_bug.cgi?id=1543769
> > > 
> > > The actual reason is that GPIO numbering used in BIOS is using "Windows"
> > > numbers meaning that they don't match the hardware 1:1 and because of
> > > this a wrong pin (backlight PWM) is picked and switched to GPIO mode.
> > > 
> > > There is a proper fix for this but since it has quite many dependencies
> > > on commits that cannot be considered stable material, I suggest we
> > > revert commit f5a26acf0162 from stable trees 4.9, 4.14 and 4.15 to
> > > prevent the backlight issue.
> > 
> > What is the "proper fix"?  Is it in Linus's tree yet?
> 
> This patch
> 
>   https://patchwork.ozlabs.org/patch/892813/
> 
> However, it is not yet in Linus' tree.

Ok, now reverted, thanks.

Oh, and 4.15.y is end-of-life, so nothing I can do there, sorry.

I pity anyone wanting to base a distro on that kernel, that would be
crazy... :)

thanks,

greg k-h