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Date: Wed, 17 Nov 2010 00:34:42 -0700
From: "Joey Lee" <jlee@...ell.com>
To: <rui.zhang@...el.com>
Cc: <mingo@...e.hu>, <lenb@...nel.org>, <airlied@...hat.com>,
<linux-acpi@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] do not select ACPI_VIDEO in poulsbo stub driver
Hi Rui,
於 三，2010-11-17 於 11:16 +0800，Zhang Rui 提到：
> On Wed, 2010-11-17 at 11:04 +0800, Joey Lee wrote:
> > Hi Rui,
> >
> > 於 三，2010-11-17 於 08:42 +0800，Zhang Rui 提到：
> > > On Tue, 2010-11-16 at 15:34 +0800, Joey Lee wrote:
> > > > Hi Rui,
> > > >
> > > > Sorry about this patch will not work on my MSi poulsbo machine.
> > > >
> > > > 於 二，2010-11-16 於 14:04 +0800，Zhang Rui 提到：
> > > > > the poulsbo stub driver should not select ACPI video driver.
> > > > >
> > > > > The reason why i915 driver selects ACPI video driver is that it needs some
> > > > > cooperation between these two drivers during initialization, or else the
> > > > > system may hang.
> > > > >
> > > > > So if users want ACPI backlight control, please set CONFIG_ACPI_VIDEO manually.
> > > > >
> > > > > http://marc.info/?l=linux-acpi&m=128952659018533&w=2
> > > > >
> > > > > CC: Ingo Molnar <mingo@...e.hu>
> > > > > CC: Dave Airlie <airlied@...hat.com>
> > > > > CC: Lee, Chun-Yi <joeyli.kernel@...il.com>
> > > > > Signed-off-by: Zhang Rui <rui.zhang@...el.com>
> > > > > ---
> > > > > drivers/gpu/stub/Kconfig | 11 +----------
> > > > > drivers/gpu/stub/poulsbo.c | 5 +----
> > > > > 2 files changed, 2 insertions(+), 14 deletions(-)
> > > > >
> > > > > Index: linux-2.6/drivers/gpu/stub/Kconfig
> > > > > ===================================================================
> > > > > --- linux-2.6.orig/drivers/gpu/stub/Kconfig
> > > > > +++ linux-2.6/drivers/gpu/stub/Kconfig
> > > > > @@ -1,16 +1,7 @@
> > > > > config STUB_POULSBO
> > > > > tristate "Intel GMA500 Stub Driver"
> > > > > depends on PCI
> > > > > - # Poulsbo stub depends on ACPI_VIDEO when ACPI is enabled
> > > > > - # but for select to work, need to select ACPI_VIDEO's dependencies, ick
> > > > > - select VIDEO_OUTPUT_CONTROL if ACPI
> > > > > - select BACKLIGHT_CLASS_DEVICE if ACPI
> > > > > - select INPUT if ACPI
> > > > > - select ACPI_VIDEO if ACPI
> > > > > help
> > > > > Choose this option if you have a system that has Intel GMA500
> > > > > (Poulsbo) integrated graphics. If M is selected, the module will
> > > > > - be called Poulsbo. This driver is a stub driver for Poulsbo that
> > > > > - will call poulsbo.ko to enable the acpi backlight control sysfs
> > > > > - entry file because there have no poulsbo native driver can support
> > > > > - intel opregion.
> > > > > + be called Poulsbo.
> > > > > Index: linux-2.6/drivers/gpu/stub/poulsbo.c
> > > > > ===================================================================
> > > > > --- linux-2.6.orig/drivers/gpu/stub/poulsbo.c
> > > > > +++ linux-2.6/drivers/gpu/stub/poulsbo.c
> > > > > @@ -11,8 +11,6 @@
> > > > >
> > > > > #include <linux/module.h>
> > > > > #include <linux/pci.h>
> > > > > -#include <linux/acpi.h>
> > > > > -#include <acpi/video.h>
> > > > >
> > > > > #define DRIVER_NAME "poulsbo"
> > > > >
> > > > > @@ -29,12 +27,11 @@ static DEFINE_PCI_DEVICE_TABLE(pciidlist
> > > > >
> > > > > static int poulsbo_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> > > > > {
> > > > > - return acpi_video_register();
> > > > > + return 0;
> > > > > }
> > > >
> > > > Sorry, we cann't remove to call acpi_video_register, because the acpi
> > > > video will not generate because there have some poulsbo machine declare
> > > > Intel opregion in DSDT but the i915 driver not support poulsbo.
> > > >
> > > I'm confused.
> > > It's the i915 driver that supports Intel Opregion.
> > > i.e. for a poulsbo machine with Intel Opregion, loading ACPI video
> > > driver won't help neither.
> > >
> >
> > Matthew have a patch:
> >
> > * http://git.kernel.org/?p=linux/kernel/git/lenb/linux-acpi-2.6.git;a=commitdiff;h=74a365b3f354fafc537efa5867deb7a9fadbfe27
> >
> > This patch do:
> >
> > - ACPI video driver will not register if it check the DSDT have opregion table declare.
> > - i915_opregion will call acpi_video_register after it initialised the DIDL field in opregion.
> >
> > That means acpi video driver will blocked when have opregion declare in
> > DSDT until i915 drm driver call acpi_video_register. The patch fixed
> > BKO#11259, but introduced a side effect: If there have Intel video chip
> > not supported by Intel drm driver, the acpi_video_register will never
> > called, then some machine have good acpi backlight interface
> > implementation will never have acpi brightness sysfs interface for
> > userland control. e.g. any Poulsbo netbook.
> >
> > Matthew's comment to talk about the side effect: Intel IGD opregion and
> > GMA500
> >
> > There have some machines declare opregion in DSDT but they also
> > implement the backlight control by EC in _BCM. Like: MSI poulsbo
> > netbook.
> > Before introduce the above patch to kernel, those machine's acpi
> > backlight control works fine. On current kernel, those machines
> > backlight control broken.
> >
> > One function workable with old kernel but broken by new kernel, now.
> >
> Oh, I see what the problem is.
> You're right, this patch doesn't make sense. Sorry for the noise. :)
>
> thanks,
> rui
No problem, and thank's for your review and take care :-)
Joey Lee
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