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

Aaron Lu
2013-07-16T03:24:04Z

On 07/15/2013 07:42 PM, Rafael J. Wysocki wrote:
> 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?

Sure.

To be clear, I actually tested the patch in your linux-next branch,
which turned out to be a little different in that you have fixed the
problem Igor raised here.

I'll ask reporters to test on a stable tree with the following two
patches on top:
https://patchwork.kernel.org/patch/2812951/ (expose OSI version)
https://patchwork.kernel.org/patch/2827793/ (your updated patch)
or your linux-next branch, whichever they like.

-Aaron

>
> 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_ */
>>>
>>