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?
thanks,
greg k-h