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Subject[PATCH 5.2 38/45] ACPI: video: Add new hw_changes_brightness quirk, set it on PB Easynote MZ35
Date
From: Hans de Goede <hdegoede@redhat.com>

[ Upstream commit 4f7f96453b462b3de0fa18d18fe983960bb5ee7f ]

Some machines change the brightness themselves when a brightness hotkey
gets pressed, despite us telling them not to. This causes the brightness to
go two steps up / down when the hotkey is pressed. This is esp. a problem
on older machines with only a few brightness levels.

This commit adds a new hw_changes_brightness quirk which makes
acpi_video_device_notify() only call backlight_force_update(...,
BACKLIGHT_UPDATE_HOTKEY) and not do anything else, notifying userspace
that the brightness was changed and leaving it at that fixing the dual
step problem.

BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=204077
Reported-by: Kacper Piwiński <cosiekvfj@o2.pl>
Tested-by: Kacper Piwiński <cosiekvfj@o2.pl>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/acpi/acpi_video.c | 37 +++++++++++++++++++++++++++++++++++++
1 file changed, 37 insertions(+)

diff --git a/drivers/acpi/acpi_video.c b/drivers/acpi/acpi_video.c
index 9489ffc064117..4f325e47519f5 100644
--- a/drivers/acpi/acpi_video.c
+++ b/drivers/acpi/acpi_video.c
@@ -60,6 +60,12 @@ module_param(report_key_events, int, 0644);
MODULE_PARM_DESC(report_key_events,
"0: none, 1: output changes, 2: brightness changes, 3: all");

+static int hw_changes_brightness = -1;
+module_param(hw_changes_brightness, int, 0644);
+MODULE_PARM_DESC(hw_changes_brightness,
+ "Set this to 1 on buggy hw which changes the brightness itself when "
+ "a hotkey is pressed: -1: auto, 0: normal 1: hw-changes-brightness");
+
/*
* Whether the struct acpi_video_device_attrib::device_id_scheme bit should be
* assumed even if not actually set.
@@ -405,6 +411,14 @@ static int video_set_report_key_events(const struct dmi_system_id *id)
return 0;
}

+static int video_hw_changes_brightness(
+ const struct dmi_system_id *d)
+{
+ if (hw_changes_brightness == -1)
+ hw_changes_brightness = 1;
+ return 0;
+}
+
static const struct dmi_system_id video_dmi_table[] = {
/*
* Broken _BQC workaround http://bugzilla.kernel.org/show_bug.cgi?id=13121
@@ -529,6 +543,21 @@ static const struct dmi_system_id video_dmi_table[] = {
DMI_MATCH(DMI_PRODUCT_NAME, "Vostro V131"),
},
},
+ /*
+ * Some machines change the brightness themselves when a brightness
+ * hotkey gets pressed, despite us telling them not to. In this case
+ * acpi_video_device_notify() should only call backlight_force_update(
+ * BACKLIGHT_UPDATE_HOTKEY) and not do anything else.
+ */
+ {
+ /* https://bugzilla.kernel.org/show_bug.cgi?id=204077 */
+ .callback = video_hw_changes_brightness,
+ .ident = "Packard Bell EasyNote MZ35",
+ .matches = {
+ DMI_MATCH(DMI_SYS_VENDOR, "Packard Bell"),
+ DMI_MATCH(DMI_PRODUCT_NAME, "EasyNote MZ35"),
+ },
+ },
{}
};

@@ -1612,6 +1641,14 @@ static void acpi_video_device_notify(acpi_handle handle, u32 event, void *data)
bus = video_device->video;
input = bus->input;

+ if (hw_changes_brightness > 0) {
+ if (video_device->backlight)
+ backlight_force_update(video_device->backlight,
+ BACKLIGHT_UPDATE_HOTKEY);
+ acpi_notifier_call_chain(device, event, 0);
+ return;
+ }
+
switch (event) {
case ACPI_VIDEO_NOTIFY_CYCLE_BRIGHTNESS: /* Cycle brightness */
brightness_switch_event(video_device, event);
--
2.20.1


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