於 三，2012-03-21 於 00:25 +0530，Pradeep Subrahmanion 提到：
> > >From 5da43d2ee6c87dcf17fda34f0b50fe11b04a16bf Mon Sep 17 00:00:00 2001
> > From: "Lee, Chun-Yi" <jlee@suse.com>
> > Date: Tue, 20 Mar 2012 19:00:58 +0800
> > Subject: [PATCH] acer-wmi: add quirk table for video backlight vendor mode
> > 
> > There have some acer laptop have broken _BCM implemenation, the AML
> > code wrote value to EC register but firmware didn't change brighenss.
> > 
> > Fortunately, the brightness control works on those machines with
> > vendor mode. So, add quirk table for video backlight vendor mode
> > and unregister acpi video interface on those machines.
> > 
> > Tested on Acer TravelMate 4750
> > 
> > Signed-off-by: Lee, Chun-Yi <jlee@suse.com>
> > ---
> >  drivers/platform/x86/Kconfig    |    4 ++++
> >  drivers/platform/x86/acer-wmi.c |   38 +++++++++++++++++++++++++++++++++++---
> >  2 files changed, 39 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> > index 15dbd8c..fe3a494 100644
> > --- a/drivers/platform/x86/Kconfig
> > +++ b/drivers/platform/x86/Kconfig
> > @@ -26,6 +26,10 @@ config ACER_WMI
> >  	depends on RFKILL || RFKILL = n
> >  	depends on ACPI_WMI
> >  	select INPUT_SPARSEKMAP
> > +	# Acer WMI depends on ACPI_VIDEO when ACPI is enabled
> > +	# but for select to work, need to select ACPI_VIDEO's dependencies, ick
> > +        select VIDEO_OUTPUT_CONTROL if ACPI
> > +        select ACPI_VIDEO if ACPI
> >  	---help---
> >  	  This is a driver for newer Acer (and Wistron) laptops. It adds
> >  	  wireless radio and bluetooth control, and on some laptops,
> > diff --git a/drivers/platform/x86/acer-wmi.c b/drivers/platform/x86/acer-wmi.c
> > index 1e5290b..984a7b5 100644
> > --- a/drivers/platform/x86/acer-wmi.c
> > +++ b/drivers/platform/x86/acer-wmi.c
> > @@ -43,6 +43,7 @@
> >  #include <linux/input/sparse-keymap.h>
> >  
> >  #include <acpi/acpi_drivers.h>
> > +#include <acpi/video.h>
> >  
> >  MODULE_AUTHOR("Carlos Corbacho");
> >  MODULE_DESCRIPTION("Acer Laptop WMI Extras Driver");
> > @@ -478,6 +479,33 @@ static struct dmi_system_id acer_quirks[] = {
> >  	{}
> >  };
> >  
> > +static int video_set_backlight_video_vendor(const struct dmi_system_id *d)
> > +{
> > +	interface->capability &= ~ACER_CAP_BRIGHTNESS;
> > +	pr_info("Brightness must be controlled by generic video driver\n");
> > +	return 0;
> > +}
> > +
> > +static const struct dmi_system_id video_vendor_dmi_table[] = {
> > +	{
> > +		.callback = video_set_backlight_video_vendor,
> > +		.ident = "Acer Aspire 4736",
> > +		.matches = {
> > +			DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
> > +			DMI_MATCH(DMI_PRODUCT_NAME, "Aspire 4736"),
> > +		},
> > +	},
> > +	{
> > +		.callback = video_set_backlight_video_vendor,
> > +		.ident = "Acer TravelMate 4750",
> > +		.matches = {
> > +			DMI_MATCH(DMI_BOARD_VENDOR, "Acer"),
> > +			DMI_MATCH(DMI_PRODUCT_NAME, "TravelMate 4750"),
> > +		},
> > +	},
> > +	{}
> > +};
> > +
> >  /* Find which quirks are needed for a particular vendor/ model pair */
> >  static void find_quirks(void)
> >  {
> > @@ -1981,9 +2009,13 @@ static int __init acer_wmi_init(void)
> >  	set_quirks();
> >  
> >  	if (acpi_video_backlight_support()) {
> > -		interface->capability &= ~ACER_CAP_BRIGHTNESS;
> > -		pr_info("Brightness must be controlled by "
> > -		       "generic video driver\n");
> > +		if (dmi_check_system(video_vendor_dmi_table)) {
> > +			acpi_video_unregister();
> > +		} else {
> > +			interface->capability &= ~ACER_CAP_BRIGHTNESS;
> > +			pr_info("Brightness must be controlled by "
> > +				"acpi video driver\n");
> > +		}
> >  	}
> >  
> >  	if (wmi_has_guid(WMID_GUID3)) {
> 
> I tried out applied your patch . Boot message shows , 
> 
> [11.220410] acer_wmi: Brightness must be controlled by generic video
> driver
> 
> Now 'acpi_video0' and 'intel_backlight' are present
> inside /sys/class/backlight .Hot key works like earlier ( ie problem
> after maximum level still exists).
> I tried following commands , 
> 

It's not the expected behavior.

This new patch should remove acpi_video0 interface on your machine.
Please kindly provide your dmidecode:
 dmidecode > dmidecode.log

And, 
please make should the patch really applied, you can do a bit change on
pr_info message by yourself.

> echo 5 > /sys/class/backlight/acpi_video0/brightness 
> echo 5 > /sys/class/backlight/intel_backlight/brightness
> 
> But it doesn't make any change . 
> 
> In my case  , 'acpi_backlight = vendor' does not make any difference since the hot key control 
> 
> already starts working with 'acpi_osi=Linux' option.
> 
> cat /proc/cmdline gives , 
> 
> BOOT_IMAGE=/boot/vmlinuz-3.3.0+
> root=UUID=f0197a59-c067-4fd8-ad90-c4d721816077 ro acpi_osi=Linux 
> 
> 
> Thanks , 
> 
> Pradeep Subrahmanion
> 

OK, that's more clearly, please remove acpi_osi=Linux then re-test, I
think the hotkey of backlight control only works with acpi_osi=Linux ?


Thanks a lot!
Joey Lee