Commit Graph

592 Commits

Author SHA1 Message Date
Thomas Hellstrom
5fd9cbad3a drm/ttm: Memory accounting rework.
Use inclusive zones to simplify accounting and its sysfs representation.
Use DMA32 accounting where applicable.

Add a sysfs interface to make the heuristically determined limits
readable and configurable.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@linux.ie>
2009-08-19 16:09:53 +10:00
Thomas Hellstrom
e9840be8c2 drm/ttm: Add a virtual ttm sysfs device.
The device directory will be the base directory of the
sysfs representation of other ttm subsystems.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@linux.ie>
2009-08-19 16:09:04 +10:00
Thomas Hellstrom
327c225bd5 drm: Enable drm drivers to add drm sysfs devices.
Export utility functions for drivers to add specialized devices in the
sysfs drm class subdirectory.

Initially this will be needed form TTM to add a virtual device that
handles power management.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Dave Airlie <airlied@linux.ie>
2009-08-19 16:08:51 +10:00
Jesse Barnes
53bd83899f drm: clarify scaling property names
Now that we're using the scaling property in the Intel driver I noticed
that the names were a bit confusing.  I've corrected them according to
our discussion on IRC and the mailing list, though I've left out
potential new additions for a new scaling property with an integer (or
two) for the scaling factor.  None of the drivers implement that today,
but if someone wants to do it, I think it could be done with the
addition of a single new type and a new property to describe the
scaling factor in the X and Y directions.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Acked-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2009-08-19 16:06:40 +10:00
Jesse Barnes
453a7d46dc drm: remove root requirement from DRM_IOCTL_SET_VERSION (+ DRM_IOCTL_AUTH_MAGIC)
Just a DRM_MASTER flag is sufficient here, though maybe this call is
totally deprecated anyway (xf86-video-intel still calls it though).

(airlied: drop ioctl auth_magic as discussed on mailing list also)

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2009-08-19 15:51:55 +10:00
Dave Airlie
cfcf4738cd drm: fixup include file in drm_encoder_slave
Signed-off-by: Dave Airlie <airlied@redhat.com>
2009-08-13 13:31:54 +10:00
Francisco Jerez
a75f023629 drm: Add more standard TV properties.
Overscan, saturation, hue. Used in the nouveau driver for GPUs with
integrated TV encoders.

Signed-off-by: Francisco Jerez <currojerez@riseup.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2009-08-13 10:33:48 +10:00
Francisco Jerez
841b4117b3 drm: Fix drm_cvt_mode() for interlaced modes.
The calculated vdisplay was half the right value.

Signed-off-by: Francisco Jerez <currojerez@riseup.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2009-08-13 10:33:37 +10:00
Francisco Jerez
b6b7902e54 drm: Define some new standard TV properties.
Namely "brightness", "contrast" and "flicker reduction".

Signed-off-by: Francisco Jerez <currojerez@riseup.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2009-08-04 14:14:46 +10:00
Francisco Jerez
aeaa1ad3ff drm: Define DRM_MODE_SUBCONNECTOR_SCART
Signed-off-by: Francisco Jerez <currojerez@riseup.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2009-08-04 14:11:00 +10:00
Francisco Jerez
74bd3c26b9 drm: Define DRM_MODE_CONNECTOR_TV
The existing TV connector types are often unsuitable either because
there is no way to probe them until they're actually plugged in or
because they can change during run time (e.g. 7-pin DIN connectors
that behave as S-Video, Component, Composite or SCART depending on the
adaptor plugged in).

Signed-off-by: Francisco Jerez <currojerez@riseup.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2009-08-04 14:10:56 +10:00
Francisco Jerez
2066facca4 drm/kms: slave encoder interface.
Define some helper functions to make easier to detach a KMS encoder
implementation from the drm module of the GPU it's used in. This is
mainly useful for some external I2C encoders known to be present on
cards with GPUs from several different manufacturers.

Signed-off-by: Francisco Jerez <currojerez@riseup.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2009-08-04 14:10:51 +10:00
Zhao Yakui
58367ed65f drm: Add the debug info in generic drm mode by using DRM_DEBUG_KMS
Add the debug info in generic drm mode by using DRM_DEBUG_KMS

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2009-08-04 14:02:51 +10:00
Zhao Yakui
f940f37f02 drm: Remove the macro defintion of DRM_DEBUG_MODE
Two macro definitions of DRM_DEBUG_KMS/MODE can be used to add the debug
info related with KMS. It is confusing.
So remove the macro definition of DRM_DEBUG_MODE. Instead it can be replaced
by the DRM_DEBUG_KMS.

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Acked-by: Ian Romanick <ian.d.romanick@intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2009-08-04 14:02:39 +10:00
Zhao Yakui
8a4c47f346 drm: Remove the unused prefix in DRM_DEBUG_KMS/DRIVER/MODE
We will have to add a prefix when using the macro defintion of DRM_DEBUG_KMS
/DRM_DEBUG_DRIVER/MODE. It is not convenient. We should use the DRM_NAME
as default prefix.
So remove the prefix in the macro definition of DRM_DEBUG_KMS/DRIVER/MODE.

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Acked-by: Ian Romanick <ian.d.romanick@intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2009-08-04 14:02:31 +10:00
Zhao Yakui
5c61259e6c drm/mode: get the modeline for standard timing in EDID by using CVT/GTF
Create the standard timing modeline by using CVT/GFT algorithm while
interpreting the EDID.

In course of interpreting the EDID, the timing level will be obtained,
which is used to determine whether the CVT/GTF algorithm is selected to
generate the modeline for the given hdisplay/vdisplay/vrefresh_rate.
In the UMS mode firstly it will check whether it can be found in
the DMT table. If it can be found, then the modeline is returned. Then the
timing_level is used to choose CVT/GTF.
As there is no DMT table, no modeline is returned when timing level
is DMT. For the other two timing levels, the CVT/GTF will be called to
generate the required standard timing modeline.

[airlied: fixed up conflicts since EDID rework]

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Dave Airlie <airlied@linux.ie>
2009-07-15 16:52:02 +10:00
Zhao Yakui
26bbdadad3 drm/mode: add the GTF algorithm in kernel space
Add the GTF algorithm in kernel space. And this function can be called to
generate the required modeline.

I copied it from the file of xserver/hw/xfree86/modes/xf86gtf.c. What I have
done is to translate it by using integer calculation. This is to avoid
the float-point calculation in kernel space.
At the same tie I also refer to the function of fb_get_mode in
drivers/video/fbmon.c

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Dave Airlie <airlied@linux.ie>
2009-07-15 16:31:43 +10:00
Zhao Yakui
d782c3f95c drm/mode: add the CVT algorithm in kernel space
Add the CVT algorithm in kernel space. And this function can be called to
generate the required modeline.

I copied it from the file of xserver/hw/xfree86/modes/xf86cvt.c. What I have
done is to translate it by using integer calculation. This is to avoid
the float-point calculation in kernel space.

[airlied:- cleaned up some bits]
Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Dave Airlie <airlied@linux.ie>
2009-07-15 16:29:33 +10:00
Zhenyu Wang
5019914ca3 drm/i915: Fix for LVDS VBT change on IGDNG
IGDNG mobile chip's LVDS data block removes panel fitting
register definition. So this fixes offset for LVDS timing
block parsing. Thanks for Michael Fu to catch this.

Signed-off-by: Zhenyu Wang <zhenyu.z.wang@intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
2009-07-10 14:11:06 -07:00
Eric Anholt
d05ca30199 drm/i915: Zap the GTT mapping when transitioning from untiled to tiled.
As of 52dc7d32b8, we could leave an old
linear GTT mapping in place, so that apps trying to GTT-mapped write in
tiled data wouldn't get the fence added, and garbage would get displayed.

Signed-off-by: Eric Anholt <eric@anholt.net>
2009-07-10 14:10:58 -07:00
Chris Wilson
901782b21e drm/i915: Refactor calls to unmap_mapping_range
As we call unmap_mapping_range() twice in identical fashion, refactor
and attempt to explain why we need to call unmap_mapping_range().

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Eric Anholt <eric@anholt.net>
2009-07-10 14:10:53 -07:00
Zhao Yakui
fccdaba431 drm/i915: Avoid saving/restore the modesetting registers twice in KMS mode
In KMS mode we now use the normal mode-setting paths to set the modes
back to the current configuration, so we don't need to also run the more
limited non-KMS implementation of modesetting for resume.

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eric Anholt <eric@anholt.net>
2009-07-10 12:40:36 -07:00
Zhao Yakui
af4fcb574e drm: Disable the unused connectors explicitly when resuming with KMS.
Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Acked-by:  Jesse Barnes <jbarnes@virtuousgeek.org>
Acked-by:  Dave Airlie <airlied@redhat.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
2009-07-10 12:39:51 -07:00
Zhao Yakui
354ff96772 drm/i915: Restore the KMS modeset for every activated CRTC
Restore the modeset for every activated CRTC in course of resume.
This is realized by calling the function of drm_helper_resume_force_mode.
Note: it is meaningful only for the KMS mode.

https://bugs.freedesktop.org/show_bug.cgi?id=21719
https://bugs.freedesktop.org/show_bug.cgi?id=21708
https://bugs.freedesktop.org/show_bug.cgi?id=22285
https://bugs.freedesktop.org/show_bug.cgi?id=22263

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
2009-07-10 12:36:11 -07:00
Eric Anholt
883e860daf drm/i915: Fix harmless warning from patch merged after i2c rework.
Signed-off-by: Eric Anholt <eric@anholt.net>
2009-07-10 12:30:18 -07:00
Eric Anholt
2a34f5e6b6 drm/i915: Disable GEM when a broken video BIOS takes up the whole aperture.
This is seen on some G41 systems, where the BIOS will consume all but
a few KB of the aperture.  This should be bad for all operating systems, as
it means that the OS can't dynamically manage memory between graphics and
the rest of the system, and OSes that did static memory management
statically add memory in addition to the BIOS allocation anyway.  So, instead
of working around it, just fail out verbosely.

fd.o bug #21574

Signed-off-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
2009-07-10 12:29:33 -07:00
Zhao Yakui
e99da35f06 drm/i915: Check the LID device to decide whether the LVDS should be initialized
On some boxes the mobile chipset is used and there is no LVDS device. In such
case we had better not initialize the LVDS output device so that one pipe can
be used for other output device. For example: E-TOP.

But unfortunately the LVDS device is still initialized on the boxes based on
mobile chipset in KMS mode. It brings that this pipe occupied by LVDS can't be
used for other output device.

After checking the acpidump we find that there is no LID device on such boxes.
In such case we can use the LID device to decide whether the LVDS device should
be initialized.

If there is no LID device, we can think that there is no LVDS device. It is
unnecessary to initialize the LVDS output device.
If there exists the LID device, it will continue the current flowchart.

Maybe on some boxes there is no LVDS device but the LID device is found. In
such case it should be added to the quirk list.

http://bugs.freedesktop.org/show_bug.cgi?id=21496
http://bugs.freedesktop.org/show_bug.cgi?id=21856
http://bugs.freedesktop.org/show_bug.cgi?id=21127

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
[anholt: squashed in style fixups]
Signed-off-by: Eric Anholt <eric@anholt.net>
2009-07-09 15:56:34 -07:00
Ben Gamari
a17458fc9d drm/i915: Move lock to more reasonable location
Make this consistent with the unlock statement. Also fix a
minor typo in debugfs formatting

Signed-off-by: Ben Gamari <bgamari.foss@gmail.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
2009-07-07 11:52:52 -07:00
Ben Gamari
a01c75b338 drm/i915: Add gtt_offset to gem object list debugfs output
This is quite useful for verifying that objects are actually mapped when
they need to be.

Signed-off-by: Ben Gamari <bgamari.foss@gmail.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
2009-07-07 11:52:48 -07:00
Ben Gamari
b5323599af drm/i915: Remove gtt_bound from drm_i915_gem_object
This wasn't even used as far as I could tell and will only confuse
people (like me).

Signed-off-by: Ben Gamari <bgamari.foss@gmail.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
2009-07-07 11:52:21 -07:00
ling.ma@intel.com
febc7694a5 drm/i915: Disable VGA output when doing DRM_MODE_DPMS_OFF.
Signed-off-by: Ma Ling <ling.ma@intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
2009-07-07 11:49:01 -07:00
ling.ma@intel.com
8e4d36b993 drm/i915: crt fetch EDID by DVI-I converter on G4x platform
Usually crt mainly get modes via GPIOA ports.
However on G4X platform we need to probe possible
ports for DVI-I, which could be wired to GPIOD,
then fetch our desired EDID, i.e on DG45ID platform
we successfully fetch EDID by GPIOD port.

It fixed freedesktop.org bug #21084

Signed-off-by: Ma Ling <ling.ma@intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
2009-07-07 11:04:22 -07:00
Zhenyu Wang
22bd50c5b9 drm/i915: Don't update display FIFO watermark on IGDNG
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
2009-07-07 10:59:16 -07:00
Keith Packard
b3d254955f drm/i915: Adjust DisplayPort clocks to use 96MHz reference
For some reason, the DP clocks were based off a 100MHz reference instead of
the standard 96MHz reference. This caused some DP monitors to fail to lock
to the signal.

Signed-off-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
2009-07-02 16:15:01 -07:00
Keith Packard
1ae8c0a56e drm/i915: Make driver less chatty
Convert many printk calls to DRM_DEBUG calls to reduce kernel log noise
for normal activities. Switch other printk calls to DRM_ERROR or DRM_INFO.

Signed-off-by: Keith Packard <keithp@keithp.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
2009-07-01 18:13:34 -07:00
Andy Whitcroft
956dba3caa drm/i915: fix up a raw 64bit divide
We are seeing compilation failures on i386 in some environments due
to an undefined reference as below:

    ERROR: "__udivdi3" [drivers/gpu/drm/i915/i915.ko] undefined!

This is generated due to a raw 64 bit divide in the i915 driver.  Fix up
this raw divide.

Signed-off-by: Andy Whitcroft <apw@canonical.com>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eric Anholt <eric@anholt.net>
2009-07-01 18:01:11 -07:00
ling.ma@intel.com
12682a9711 drm/i915: enable sdvo lvds scaling function.
Currently we implemented basic sdvo lvds function,
But except for sdvo lvds fixed mode, we can not switch
to other modes, otherwise display get black. The patch
handle three operations to enable sdvo lvds. At first
duplicate sdvo fixed mode for adjustment, then according
to fixed mode line valid all modes, at last adjust input
mode to fit our requirement.

Acked by Li Peng <peng.li@linux.intel.com>
Signed-off-by: Ma Ling <ling.ma@intel.com>
Reviewed-by: Ian Romanick <idr@freedesktop.org>
Signed-off-by: Eric Anholt <eric@anholt.net>
2009-07-01 11:44:45 -07:00
ling.ma@intel.com
6ff4fd0567 drm/i915: Set SSC frequency for 8xx chips correctly
All 8xx class chips have the 66/48 split, not just 855.

Signed-off-by: Ma Ling <ling.ma@intel.com>
Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eric Anholt <eric@anholt.net>
2009-07-01 11:20:44 -07:00
Shaohua Li
7662c8bd65 drm/i915: add FIFO watermark support
This patch from jbarnes and myself adds FIFO watermark control to the
driver.  This is needed for both power saving features on new platforms
with the so-called "big FIFO" and for controlling FIFO allocation
between pipes in multi-head configurations.

It's also necessary infrastructure to support things like framebuffer
compression and configuration supportability checks (i.e. checking a
configuration against available bandwidth).

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
2009-07-01 11:16:09 -07:00
Jesse Barnes
63eeaf3825 drm/i915: enable error detection & state collection
This patch enables error detection by enabling several types of error
interrupts.  When an error interrupt is received, the interrupt
handler captures the error state; hopefully resulting in an accurate
set of error data (error type, active head pointer, etc.).  The new
record is then available from sysfs.  The current code will also dump
the error state to the system log.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eric Anholt <eric@anholt.net>
2009-07-01 10:50:02 -07:00
Linus Torvalds
987fed3bf6 Merge branch 'drm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6
* 'drm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6: (28 commits)
  drm: remove unused #include <linux/version.h>'s
  drm/radeon: fix driver initialization order so radeon kms can be builtin
  drm: Fix shifts which were miscalculated when converting from bitfields.
  drm/radeon: Clear surface registers at initialization time.
  drm/radeon: Don't initialize acceleration related fields of struct fb_info.
  drm/radeon: fix radeon kms framebuffer device
  drm/i915: initialize fence registers to zero when loading GEM
  drm/i915: Fix HDMI regression introduced in new chipset support
  drm/i915: fix LFP data fetch
  drm/i915: set TV detection mode when tv is already connected
  drm/i915: Catch up to obj_priv->page_list rename in disabled debug code.
  drm/i915: Fix size_t handling in off-by-default debug printfs
  drm/i915: Don't change the blank/sync width when calculating scaled modes
  drm/i915: Add support for changing LVDS panel fitting using an output property.
  drm/i915: correct suspend/resume ordering
  drm/i915: Add missing dependency on Intel AGP support.
  drm/i915: Generate 2MHz clock for display port aux channel I/O. Retry I/O.
  drm/i915: Clarify error returns from display port aux channel I/O
  drm/i915: Add CLKCFG register definition
  drm/i915: Split array of DAC limits into separate structures.
  ...
2009-06-25 17:04:37 -07:00
Huang Weiyi
8b169b5f1f drm: remove unused #include <linux/version.h>'s
Remove unused #include <linux/version.h>('s) in
 drivers/gpu/drm/ttm/ttm_bo_util.c
 drivers/gpu/drm/ttm/ttm_bo_vm.c
 drivers/gpu/drm/ttm/ttm_tt.c

Signed-off-by: Huang Weiyi <weiyi.huang@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2009-06-24 16:31:50 +10:00
Dave Airlie
5b6345be1b Merge remote branch 'origin/drm-intel-next' of ../drm-intel into drm-fixes 2009-06-24 16:20:19 +10:00
Jerome Glisse
176f613e60 drm/radeon: fix driver initialization order so radeon kms can be builtin
TTM need to be initialized before radeon if KMS is enabled otherwise
the kernel will crash hard.

Signed-off-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Dave Airlie <airlied@linux.ie>
2009-06-24 16:11:06 +10:00
Michel Dänzer
e14cbee401 drm: Fix shifts which were miscalculated when converting from bitfields.
Looks like I managed to mess up most shifts when converting from bitfields. :(

The patch below works on my Thinkpad T500 (as well as on my PowerBook,
where the previous change worked as well, maybe out of luck...). I'd
appreciate more testing and eyes looking over it though.

Signed-off-by: Michel Dänzer <daenzer@vmware.com>
Tested-by: Michael Pyne <mpyne@kde.org>
Signed-off-by: Dave Airlie <airlied@linux.ie>
2009-06-24 16:11:04 +10:00
Michel Dänzer
b1e3a6d1c4 drm/radeon: Clear surface registers at initialization time.
Some PowerMac firmwares set up a tiling surface at the beginning of VRAM
which messes us up otherwise.

Signed-off-by: Michel Dänzer <daenzer@vmware.com>
Signed-off-by: Dave Airlie <airlied@linux.ie>
2009-06-24 16:10:56 +10:00
Michel Dänzer
696d4df1db drm/radeon: Don't initialize acceleration related fields of struct fb_info.
Might lure userspace into trying silly things otherwise.

Signed-off-by: Michel Dänzer <daenzer@vmware.com>
Signed-off-by: Dave Airlie <airlied@linux.ie>
2009-06-24 16:09:52 +10:00
Jerome Glisse
f92e93eb5f drm/radeon: fix radeon kms framebuffer device
smem.start is a physical address which kernel can remap to access
video memory of the fb buffer. We now pin the fb buffer into vram
by doing so we are loosing vram but fbdev need to be reworked to
allow change in framebuffer address.

Signed-off-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Dave Airlie <airlied@linux.ie>
2009-06-24 16:09:41 +10:00
Len Brown
fbe8cddd2d Merge branches 'acerhdf', 'acpi-pci-bind', 'bjorn-pci-root', 'bugzilla-12904', 'bugzilla-13121', 'bugzilla-13396', 'bugzilla-13533', 'bugzilla-13612', 'c3_lock', 'hid-cleanups', 'misc-2.6.31', 'pdc-leak-fix', 'pnpacpi', 'power_nocheck', 'thinkpad_acpi', 'video' and 'wmi' into release 2009-06-24 01:19:50 -04:00
Zhao Yakui
86e437f077 ACPI: Add the reference count to avoid unloading ACPI video bus twice
Sometimes both acpi video and i915 driver are compiled as modules.
And there exists the strict dependency between the two drivers.
The acpi video bus will be unloaded in course of unloading the i915 driver.
If we unload the acpi video driver, then the kernel oops will be triggered.

Add the reference count to avoid unloading the ACPI video bus twice.
The reference count should be checked before unregistering the acpi video bus.
If the reference count is already zero, it won't unregister it again.
And after the acpi video bus is already unregistered, the reference count
will be set to zero.

http://bugzilla.kernel.org/show_bug.cgi?id=13396

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Acked-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
2009-06-23 23:38:41 -04:00