From: James Hogan <jhogan@kernel.org>
To: Hans de Goede <hdegoede@redhat.com>
Cc: Zhang Rui <rui.zhang@intel.com>,
"Rafael J . Wysocki" <rjw@rjwysocki.net>,
Len Brown <lenb@kernel.org>,
linux-acpi@vger.kernel.org, stable@vger.kernel.org,
Sasha Levin <alexander.levin@microsoft.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [REGRESSION] [v2] ACPI / video: Default lcd_only to true on Win8 ready and newer machines
Date: Mon, 16 Apr 2018 14:02:12 +0100 [thread overview]
Message-ID: <20180416130211.GA484@jamesdev> (raw)
In-Reply-To: <18c72a70-577f-358e-fb82-095b75157a29@redhat.com>
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On Mon, Apr 16, 2018 at 01:07:50PM +0200, Hans de Goede wrote:
> On 16-04-18 00:54, James Hogan wrote:
> > On Sun, Apr 15, 2018 at 02:04:26PM +0200, Hans de Goede wrote:
> > > When you say quirk do you mean you add something to
> > > the kernel commandline to work around this?
> >
> > No, it was automatic, in the source. I don't know this code well enough
> > to know how they got it working.
>
> Weird, if my only_lcd changes impact you then acpi_osi_is_win8()
> returns true for you
It rings a bell that this laptop claims win8 support.
> you should get the intel backlight interface
> by default, but maybe the i915 driver somehow detects that that
> is not appropriate on your device ... ?
>
> Before I can start working on a quirk to fix this I've some
> questions:
>
> 1) With recent kernels without the 965736ee654d commit, what is
> the output of "ls /sys/class/backlight" ?
$ ls -l /sys/class/backlight
total 0
lrwxrwxrwx 1 root root 0 Apr 16 13:57 acpi_video0 -> ../../devices/pci0000:00/0000:00:02.0/backlight/acpi_video0
> 2) What is the output of "ls /sys/class/backlight" after
> commit 965736ee654d ?
no devices show up there.
> 3) Can you start a kernel with commit 965736ee654d in there and
> "video.only_lcd=0" on the kernel commandline and verify that
> this fixes backlight control for you ?
Confirmed, acpi_video0 shows up and backlight control works as expected.
Cheers
James
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next prev parent reply other threads:[~2018-04-16 13:02 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20171223184147.12016-1-hdegoede@redhat.com>
2018-04-14 23:07 ` [REGRESSION] [v2] ACPI / video: Default lcd_only to true on Win8 ready and newer machines James Hogan
2018-04-15 12:04 ` Hans de Goede
2018-04-15 22:54 ` James Hogan
2018-04-16 11:07 ` Hans de Goede
2018-04-16 13:02 ` James Hogan [this message]
2018-04-17 15:20 ` Hans de Goede
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