[PATCH 1/1] drm: i915: don't use OpRegion for XPS 13 IvyBridge

[Andrea Arcangeli]

On Thu, Sep 08, 2016 at 01:09:23PM +0200, Martin van Es wrote:
> On donderdag 8 september 2016 13:18:41 CEST Ville Syrjälä wrote:
> > On Thu, Sep 08, 2016 at 12:04:39PM +0200, Martin van Es wrote:
> > > On dinsdag 6 september 2016 21:40:48 CEST Ville Syrjälä wrote:
> > > > On Tue, Sep 06, 2016 at 01:56:20PM +0300, Ville Syrjälä wrote:
> > > > > Actually I just cooked up another branch [2]. It just throws in some
> > > > > memory barriers to the opregion code, and adds a a new debug print so
> > > > > to show the response from the BIOS. I'm not too optimistic that the
> > > > > memory barriers would fix it, but at least we'd get to see the full
> > > > > response from the BIOS. Can you give this a try?
> > > > > 
> > > > > [2] git://github.com/vsyrjala/linux.git opregion_panel_type_stuff
> > > 
> > > This kernel doesn't boot (for me).
> > > 
> > > I cloned the repo, copied .config from 4.7 kernel, make oldconfig,
> > > accepted
> > > all defaults and made+installed the kernel. This installed an image
> > > 4.0.0-rc7+ (is that correct?) that was unbootable (halts at loading
> > > ramdisk).
> > The version should be 4.7 or 4.8 something. Maybe you used the wrong
> > branch?
> 
> Oh silly me and git. I thought I'd be checking out the correct branch on 
> cloning that repo. I now checked out opregion_panel_type_quirk branch and that 
> resulted in a 4.8.0-rc5+ kernel.
> 
> Booting that kernel resulted in a correct functioning backlight based on 
> acpi_video0 driver. Graphics glitches however were so bad I had to reboot into 
> 4.7.3 to write this mail.
> 
> dmesg of 4.8.0-rc5+ boot with drm.debug=0xe attached.

Thanks Martin.

I was in vacation last week, let me know if you need me to test as
well but me and Martin are reproducing the exact same issue so I
believe his testing should have provided all info needed for now.

While talking about graphics glitches this reminds I'm getting
corrupted graphics on terminals (sandy bridge HD3000) with any intel
driver >=x11-drivers/xf86-video-intel-2.99.917_p20160803

I had to add:

cat /etc/portage/package.mask/x11
>=x11-drivers/xf86-video-intel-2.99.917_p20160803

Last working version for me is:

qlist -I -v video-intel
x11-drivers/xf86-video-intel-2.99.917_p20160704

That is most certainly an unrelated issue with the backlight, and I'm
not even sure if it affects the Ivy Bridge laptop with hd4000, as I
ended up never testing anything above 2.99.917_p20160704 on it. But in
my experience you may want to try to downgrade the xorg intel video
driver version too if you get graphic glitches.