Bug 36114

Summary:	Dimming Laptop LCD causes buzz
Product:	xorg	Reporter:	geeksanonymouse
Component:	Driver/nouveau	Assignee:	Nouveau Project <nouveau>
Status:	RESOLVED INVALID	QA Contact:	Xorg Project Team <xorg-team>
Severity:	normal
Priority:	medium
Version:	unspecified
Hardware:	x86-64 (AMD64)
OS:	Linux (All)
Whiteboard:	2011BRB_Reviewed
i915 platform:		i915 features:

Description geeksanonymouse 2011-04-10 07:04:11 UTC

Vaio F11: i7-720 QM, Nvidia GT330m
OS: Arch Linux, openSuse 11.4

When X is running, if I dim my screen by changing the value in /sys/devices/virtual/backlight/acpi_video0/brightness my LCD emits a high pitched buzz. I boot up to a terminal and I can change the brightness without getting the buzz. However, when X is running, I get the buzz.
The buzz does not occur in Windows 7 with any brightness setting. 

Steps to reproduce:
Boot up Linux distro to terminal.
sudo vi /sys/devices/virtual/backlight/acpi_video0/brightness
    change 8 to anything lower than 8 but greater than 0
Screen dims, no buzz.
Reset brightness to 8.
startx
Change brightness to less than 8.
Listen to buzz.

Comment 1 Ilia Mirkin 2015-05-08 05:30:27 UTC

This bug is many years old. Closing, as there has been no activity. Feel free to reopen if this still happens with recent software versions, make sure to include logs.

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