113 lines
4.3 KiB
Diff
113 lines
4.3 KiB
Diff
Bugzilla: 1012674
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Upstream-status: Queued for 3.16
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From 4cf3eac89ed731d7cdb7d9d815a97109472af824 Mon Sep 17 00:00:00 2001
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From: Hans de Goede <hdegoede@redhat.com>
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Date: Mon, 2 Jun 2014 17:41:04 +0200
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Subject: [PATCH 07/14] acpi-video: Add an acpi_video_unregister_backlight
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function
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Add an acpi_video_unregister_backlight function, which only unregisters
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the backlight device, and leaves the acpi_notifier in place. Some acpi_vendor
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driver need this as they don't want the acpi_video# backlight device, but do
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need the acpi-video driver for hotkey handling.
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Chances are that this new acpi_video_unregister_backlight() is actually
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what existing acpi_vendor drivers have wanted all along. Currently acpi_vendor
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drivers which want to disable the acpi_video# backlight device, make 2 calls:
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acpi_video_dmi_promote_vendor();
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acpi_video_unregister();
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The intention here is to make things independent of when acpi_video_register()
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gets called. As acpi_video_register() will get called on acpi-video load time
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on non intel gfx machines, while it gets called on i915 load time on intel
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gfx machines.
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This leads to the following 2 interesting scenarios:
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a) intel gfx:
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1) acpi-video module gets loaded (as it is a dependency of acpi_vendor and i915)
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2) acpi-video does NOT call acpi_video_register()
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3) acpi_vendor loads (lets assume it loads before i915), calls
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acpi_video_dmi_promote_vendor(); which sets ACPI_VIDEO_BACKLIGHT_DMI_VENDOR
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4) calls acpi_video_unregister -> not registered, nop
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5) i915 loads, calls acpi_video_register
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6) acpi_video_register registers the acpi_notifier for the hotkeys,
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does NOT register a backlight device because of ACPI_VIDEO_BACKLIGHT_DMI_VENDOR
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b) non intel gfx
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1) acpi-video module gets loaded (as it is a dependency acpi_vendor)
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2) acpi-video calls acpi_video_register()
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3) acpi_video_register registers the acpi_notifier for the hotkeys,
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and a backlight device
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4) acpi_vendor loads, calls acpi_video_dmi_promote_vendor()
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5) calls acpi_video_unregister, this unregisters BOTH the acpi_notifier for
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the hotkeys AND the backlight device
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So here we have possibly the same acpi_vendor module, making the same calls,
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but with different results, in one cases acpi-video does handle hotkeys,
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in the other it does not.
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Note that the a) scenario turns into b) if we assume the i915 module loads
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before the vendor_acpi module, so we also have different behavior depending
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on module loading order!
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So as said I believe that quite a few existing acpi_vendor modules really
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always want the behavior of a), hence this patch adds a new
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acpi_video_unregister_backlight() which gives the behavior of a) independent
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of module loading order.
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Signed-off-by: Hans de Goede <hdegoede@redhat.com>
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---
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drivers/acpi/video.c | 14 ++++++++++++++
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include/acpi/video.h | 2 ++
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2 files changed, 16 insertions(+)
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diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
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index a68313720c9c..d4d6ea3ac77a 100644
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--- a/drivers/acpi/video.c
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+++ b/drivers/acpi/video.c
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@@ -2070,6 +2070,20 @@ void acpi_video_unregister(void)
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}
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EXPORT_SYMBOL(acpi_video_unregister);
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+void acpi_video_unregister_backlight(void)
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+{
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+ struct acpi_video_bus *video;
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+
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+ if (!register_count)
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+ return;
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+
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+ mutex_lock(&video_list_lock);
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+ list_for_each_entry(video, &video_bus_head, entry)
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+ acpi_video_bus_unregister_backlight(video);
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+ mutex_unlock(&video_list_lock);
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+}
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+EXPORT_SYMBOL(acpi_video_unregister_backlight);
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+
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/*
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* This is kind of nasty. Hardware using Intel chipsets may require
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* the video opregion code to be run first in order to initialise
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diff --git a/include/acpi/video.h b/include/acpi/video.h
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index 61109f2609fc..ea4c7bbded4d 100644
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--- a/include/acpi/video.h
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+++ b/include/acpi/video.h
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@@ -19,11 +19,13 @@ struct acpi_device;
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#if (defined CONFIG_ACPI_VIDEO || defined CONFIG_ACPI_VIDEO_MODULE)
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extern int acpi_video_register(void);
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extern void acpi_video_unregister(void);
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+extern void acpi_video_unregister_backlight(void);
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extern int acpi_video_get_edid(struct acpi_device *device, int type,
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int device_id, void **edid);
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#else
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static inline int acpi_video_register(void) { return 0; }
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static inline void acpi_video_unregister(void) { return; }
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+static inline void acpi_video_unregister_backlight(void) { return; }
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static inline int acpi_video_get_edid(struct acpi_device *device, int type,
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int device_id, void **edid)
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{
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--
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1.9.0
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