Re: [Update][PATCH] ACPI / video / i915: Remove ACPI backlight if firmware expects Windows 8

Rafael J. Wysocki
2013-07-15T11:32:23Z

On Monday, July 15, 2013 10:36:15 AM Aaron Lu wrote:
> On 07/13/2013 08:46 AM, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> >
> > According to Matthew Garrett, "Windows 8 leaves backlight control up
> > to individual graphics drivers rather than making ACPI calls itself.
> > There's plenty of evidence to suggest that the Intel driver for
> > Windows [8] doesn't use the ACPI interface, including the fact that
> > it's broken on a bunch of machines when the OS claims to support
> > Windows 8. The simplest thing to do appears to be to disable the
> > ACPI backlight interface on these systems".
> >
> > There's a problem with that approach, however, because simply
> > avoiding to register the ACPI backlight interface if the firmware
> > calls _OSI for Windows 8 may not work in the following situations:
> > (1) The ACPI backlight interface actually works on the given system
> > and the i915 driver is not loaded (e.g. another graphics driver
> > is used).
> > (2) The ACPI backlight interface doesn't work on the given system,
> > but there is a vendor platform driver that will register its
> > own, equally broken, backlight interface if not prevented from
> > doing so by the ACPI subsystem.
> > Therefore we need to allow the ACPI backlight interface to be
> > registered until the i915 driver is loaded which then will unregister
> > it if the firmware has called _OSI for Windows 8 (or will register
> > the ACPI video driver without backlight support if not already
> > present).
> >
> > For this reason, introduce an alternative function for registering
> > ACPI video, acpi_video_register_with_quirks(), that will check
> > whether or not the ACPI video driver has already been registered
> > and whether or not the backlight Windows 8 quirk has to be applied.
> > If the quirk has to be applied, it will block the ACPI backlight
> > support and either unregister the backlight interface if the ACPI
> > video driver has already been registered, or register the ACPI
> > video driver without the backlight interface otherwise. Make
> > the i915 driver use acpi_video_register_with_quirks() instead of
> > acpi_video_register() in i915_driver_load().
> >
> > This change is based on earlier patches from Matthew Garrett,
> > Chun-Yi Lee and Seth Forshee and Aaron Lu's comments.
> >
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> Reviewed-by: Aaron Lu <aaron.lu@intel.com>
>
> BTW, I also tested on a Toshiba laptop Z830 where its AML code
> claims support of win8, the result is as expected: ACPI video
> interface is removed, i915 Xorg driver picks intel_backlight.
>
> Thanks for the fix.

Cool, thanks for testing this!

Can you please also ask bug reporters in the BZ entires related to this to test
it too?

Rafael

> > ---
> > drivers/acpi/internal.h | 11 ++++++
> > drivers/acpi/video.c | 65 ++++++++++++++++++++++++++++++++++++----
> > drivers/acpi/video_detect.c | 21 ++++++++++++
> > drivers/gpu/drm/i915/i915_dma.c | 2 -
> > include/acpi/video.h | 11 ++++++
> > include/linux/acpi.h | 1
> > 6 files changed, 103 insertions(+), 8 deletions(-)
> >
> > Index: linux-pm/drivers/acpi/video.c
> > ===================================================================
> > --- linux-pm.orig/drivers/acpi/video.c
> > +++ linux-pm/drivers/acpi/video.c
> > @@ -44,6 +44,8 @@
> > #include <linux/suspend.h>
> > #include <acpi/video.h>
> >
> > +#include "internal.h"
> > +
> > #define PREFIX "ACPI: "
> >
> > #define ACPI_VIDEO_BUS_NAME "Video Bus"
> > @@ -898,7 +900,7 @@ static void acpi_video_device_find_cap(s
> > device->cap._DDC = 1;
> > }
> >
> > - if (acpi_video_backlight_support()) {
> > + if (acpi_video_verify_backlight_support()) {
> > struct backlight_properties props;
> > struct pci_dev *pdev;
> > acpi_handle acpi_parent;
> > @@ -1854,6 +1856,46 @@ static int acpi_video_bus_remove(struct
> > return 0;
> > }
> >
> > +static acpi_status video_unregister_backlight(acpi_handle handle, u32 lvl,
> > + void *context, void **rv)
> > +{
> > + struct acpi_device *acpi_dev;
> > + struct acpi_video_bus *video;
> > + struct acpi_video_device *dev, *next;
> > +
> > + if (acpi_bus_get_device(handle, &acpi_dev))
> > + return AE_OK;
> > +
> > + if (acpi_match_device_ids(acpi_dev, video_device_ids))
> > + return AE_OK;
> > +
> > + video = acpi_driver_data(acpi_dev);
> > + if (!video)
> > + return AE_OK;
> > +
> > + acpi_video_bus_stop_devices(video);
> > + mutex_lock(&video->device_list_lock);
> > + list_for_each_entry_safe(dev, next, &video->video_device_list, entry) {
> > + if (dev->backlight) {
> > + backlight_device_unregister(dev->backlight);
> > + dev->backlight = NULL;
> > + kfree(dev->brightness->levels);
> > + kfree(dev->brightness);
> > + }
> > + if (dev->cooling_dev) {
> > + sysfs_remove_link(&dev->dev->dev.kobj,
> > + "thermal_cooling");
> > + sysfs_remove_link(&dev->cooling_dev->device.kobj,
> > + "device");
> > + thermal_cooling_device_unregister(dev->cooling_dev);
> > + dev->cooling_dev = NULL;
> > + }
> > + }
> > + mutex_unlock(&video->device_list_lock);
> > + acpi_video_bus_start_devices(video);
> > + return AE_OK;
> > +}
> > +
> > static int __init is_i740(struct pci_dev *dev)
> > {
> > if (dev->device == 0x00D1)
> > @@ -1885,14 +1927,25 @@ static int __init intel_opregion_present
> > return opregion;
> > }
> >
> > -int acpi_video_register(void)
> > +int __acpi_video_register(bool backlight_quirks)
> > {
> > - int result = 0;
> > + bool no_backlight;
> > + int result;
> > +
> > + no_backlight = backlight_quirks ? acpi_video_backlight_quirks() : false;
> > +
> > if (register_count) {
> > /*
> > - * if the function of acpi_video_register is already called,
> > - * don't register the acpi_vide_bus again and return no error.
> > + * If acpi_video_register() has been called already, don't try
> > + * to register acpi_video_bus, but unregister backlight devices
> > + * if no backlight support is requested.
> > */
> > + if (no_backlight)
> > + acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
> > + ACPI_UINT32_MAX,
> > + video_unregister_backlight,
> > + NULL, NULL, NULL);
> > +
> > return 0;
> > }
> >
> > @@ -1908,7 +1961,7 @@ int acpi_video_register(void)
> >
> > return 0;
> > }
> > -EXPORT_SYMBOL(acpi_video_register);
> > +EXPORT_SYMBOL(__acpi_video_register);
> >
> > void acpi_video_unregister(void)
> > {
> > Index: linux-pm/drivers/gpu/drm/i915/i915_dma.c
> > ===================================================================
> > --- linux-pm.orig/drivers/gpu/drm/i915/i915_dma.c
> > +++ linux-pm/drivers/gpu/drm/i915/i915_dma.c
> > @@ -1660,7 +1660,7 @@ int i915_driver_load(struct drm_device *
> > if (INTEL_INFO(dev)->num_pipes) {
> > /* Must be done after probing outputs */
> > intel_opregion_init(dev);
> > - acpi_video_register();
> > + acpi_video_register_with_quirks();
> > }
> >
> > if (IS_GEN5(dev))
> > Index: linux-pm/include/acpi/video.h
> > ===================================================================
> > --- linux-pm.orig/include/acpi/video.h
> > +++ linux-pm/include/acpi/video.h
> > @@ -17,12 +17,21 @@ struct acpi_device;
> > #define ACPI_VIDEO_DISPLAY_LEGACY_TV 0x0200
> >
> > #if (defined CONFIG_ACPI_VIDEO || defined CONFIG_ACPI_VIDEO_MODULE)
> > -extern int acpi_video_register(void);
> > +extern int __acpi_video_register(bool backlight_quirks);
> > +static inline int acpi_video_register(void)
> > +{
> > + return __acpi_video_register(false);
> > +}
> > +static inline int acpi_video_register_with_quirks(void)
> > +{
> > + return __acpi_video_register(true);
> > +}
> > extern void acpi_video_unregister(void);
> > extern int acpi_video_get_edid(struct acpi_device *device, int type,
> > int device_id, void **edid);
> > #else
> > static inline int acpi_video_register(void) { return 0; }
> > +static inline int acpi_video_register_with_quirks(void) { return 0; }
> > static inline void acpi_video_unregister(void) { return; }
> > static inline int acpi_video_get_edid(struct acpi_device *device, int type,
> > int device_id, void **edid)
> > Index: linux-pm/drivers/acpi/video_detect.c
> > ===================================================================
> > --- linux-pm.orig/drivers/acpi/video_detect.c
> > +++ linux-pm/drivers/acpi/video_detect.c
> > @@ -38,6 +38,8 @@
> > #include <linux/dmi.h>
> > #include <linux/pci.h>
> >
> > +#include "internal.h"
> > +
> > #define PREFIX "ACPI: "
> >
> > ACPI_MODULE_NAME("video");
> > @@ -234,6 +236,17 @@ static void acpi_video_caps_check(void)
> > acpi_video_get_capabilities(NULL);
> > }
> >
> > +bool acpi_video_backlight_quirks(void)
> > +{
> > + if (acpi_gbl_osi_data >= ACPI_OSI_WIN_8) {
> > + acpi_video_caps_check();
> > + acpi_video_support |= ACPI_VIDEO_SKIP_BACKLIGHT;
> > + return true;
> > + }
> > + return false;
> > +}
> > +EXPORT_SYMBOL(acpi_video_backlight_quirks);
> > +
> > /* Promote the vendor interface instead of the generic video module.
> > * This function allow DMI blacklists to be implemented by externals
> > * platform drivers instead of putting a big blacklist in video_detect.c
> > @@ -278,6 +291,14 @@ int acpi_video_backlight_support(void)
> > }
> > EXPORT_SYMBOL(acpi_video_backlight_support);
> >
> > +/* For the ACPI video driver's use only. */
> > +bool acpi_video_verify_backlight_support(void)
> > +{
> > + return (acpi_video_support & ACPI_VIDEO_SKIP_BACKLIGHT) ?
> > + false : acpi_video_backlight_support();
> > +}
> > +EXPORT_SYMBOL(acpi_video_verify_backlight_support);
> > +
> > /*
> > * Use acpi_backlight=vendor/video to force that backlight switching
> > * is processed by vendor specific acpi drivers or video.ko driver.
> > Index: linux-pm/include/linux/acpi.h
> > ===================================================================
> > --- linux-pm.orig/include/linux/acpi.h
> > +++ linux-pm/include/linux/acpi.h
> > @@ -191,6 +191,7 @@ extern bool wmi_has_guid(const char *gui
> > #define ACPI_VIDEO_BACKLIGHT_DMI_VIDEO 0x0200
> > #define ACPI_VIDEO_OUTPUT_SWITCHING_DMI_VENDOR 0x0400
> > #define ACPI_VIDEO_OUTPUT_SWITCHING_DMI_VIDEO 0x0800
> > +#define ACPI_VIDEO_SKIP_BACKLIGHT 0x1000
> >
> > #if defined(CONFIG_ACPI_VIDEO) || defined(CONFIG_ACPI_VIDEO_MODULE)
> >
> > Index: linux-pm/drivers/acpi/internal.h
> > ===================================================================
> > --- linux-pm.orig/drivers/acpi/internal.h
> > +++ linux-pm/drivers/acpi/internal.h
> > @@ -164,4 +164,15 @@ struct platform_device;
> > int acpi_create_platform_device(struct acpi_device *adev,
> > const struct acpi_device_id *id);
> >
> > +/*--------------------------------------------------------------------------
> > + Video
> > + -------------------------------------------------------------------------- */
> > +#ifdef CONFIG_ACPI_VIDEO
> > +bool acpi_video_backlight_quirks(void);
> > +bool acpi_video_verify_backlight_support(void);
> > +#else
> > +static inline bool acpi_video_backlight_quirks(void) { return false; }
> > +static inline bool acpi_video_verify_backlight_support(void) { return false; }
> > +#endif
> > +
> > #endif /* _ACPI_INTERNAL_H_ */
> >
>
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.