Re: [PATCH 1/5] Backlight: Add backlight type

Re: [PATCH 1/5] Backlight: Add backlight type

[Sedat Dilek]

[...]
+What:		/sys/class/backlight/<backlight>/type
+Date:		September 2010
+KernelVersion:	2.6.37
[...]

2.6.37?
Will this go into 2.6.38? 2.6.39?

Through which subsystem will these patches walk through? drm-2.6?
platform-drivers-x86?
Are you planning a GIT tree/branch for this patch-set?

The patch-set from 14-Jan-2011 applies against linux-next (next-20110115).
I will compile, test and report.

- Sedat -

[PATCH 1/5] Backlight: Add backlight type

[Matthew Garrett]

There may be multiple ways of controlling the backlight on a given machine.
Allow drivers to expose the type of interface they are providing, making
it possible for userspace to make appropriate policy decisions.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: intel-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
---
 Documentation/ABI/stable/sysfs-class-backlight     |   20 ++++++++++++++++
 drivers/acpi/video.c                               |    1 +
 drivers/gpu/drm/nouveau/nouveau_backlight.c        |    2 +
 drivers/hid/hid-picolcd.c                          |    1 +
 drivers/macintosh/via-pmu-backlight.c              |    1 +
 drivers/platform/x86/acer-wmi.c                    |    1 +
 drivers/platform/x86/asus-laptop.c                 |    1 +
 drivers/platform/x86/asus_acpi.c                   |    1 +
 drivers/platform/x86/classmate-laptop.c            |    1 +
 drivers/platform/x86/compal-laptop.c               |    1 +
 drivers/platform/x86/dell-laptop.c                 |    1 +
 drivers/platform/x86/eeepc-laptop.c                |    1 +
 drivers/platform/x86/eeepc-wmi.c                   |    1 +
 drivers/platform/x86/fujitsu-laptop.c              |    1 +
 drivers/platform/x86/msi-laptop.c                  |    1 +
 drivers/platform/x86/msi-wmi.c                     |    1 +
 drivers/platform/x86/panasonic-laptop.c            |    1 +
 drivers/platform/x86/sony-laptop.c                 |    1 +
 drivers/platform/x86/thinkpad_acpi.c               |    1 +
 drivers/platform/x86/toshiba_acpi.c                |    1 +
 drivers/staging/olpc_dcon/olpc_dcon.c              |    1 +
 drivers/staging/samsung-laptop/samsung-laptop.c    |    1 +
 drivers/usb/misc/appledisplay.c                    |    1 +
 drivers/video/atmel_lcdfb.c                        |    1 +
 drivers/video/aty/aty128fb.c                       |    1 +
 drivers/video/aty/atyfb_base.c                     |    1 +
 drivers/video/aty/radeon_backlight.c               |    1 +
 drivers/video/backlight/88pm860x_bl.c              |    1 +
 drivers/video/backlight/adp5520_bl.c               |    1 +
 drivers/video/backlight/adp8860_bl.c               |    1 +
 drivers/video/backlight/adx_bl.c                   |    1 +
 drivers/video/backlight/atmel-pwm-bl.c             |    1 +
 drivers/video/backlight/backlight.c                |   24 +++++++++++++++++++-
 drivers/video/backlight/corgi_lcd.c                |    1 +
 drivers/video/backlight/cr_bllcd.c                 |    1 +
 drivers/video/backlight/da903x_bl.c                |    1 +
 drivers/video/backlight/ep93xx_bl.c                |    1 +
 drivers/video/backlight/generic_bl.c               |    1 +
 drivers/video/backlight/hp680_bl.c                 |    1 +
 drivers/video/backlight/jornada720_bl.c            |    1 +
 drivers/video/backlight/kb3886_bl.c                |    1 +
 drivers/video/backlight/locomolcd.c                |    1 +
 drivers/video/backlight/max8925_bl.c               |    1 +
 drivers/video/backlight/mbp_nvidia_bl.c            |    1 +
 drivers/video/backlight/omap1_bl.c                 |    1 +
 drivers/video/backlight/pcf50633-backlight.c       |    1 +
 drivers/video/backlight/progear_bl.c               |    1 +
 drivers/video/backlight/pwm_bl.c                   |    1 +
 drivers/video/backlight/s6e63m0.c                  |    1 +
 drivers/video/backlight/tosa_bl.c                  |    1 +
 drivers/video/backlight/wm831x_bl.c                |    1 +
 drivers/video/bf54x-lq043fb.c                      |    1 +
 drivers/video/bfin-t350mcqb-fb.c                   |    1 +
 drivers/video/imxfb.c                              |    1 +
 drivers/video/nvidia/nv_backlight.c                |    1 +
 drivers/video/omap2/displays/panel-acx565akm.c     |    1 +
 .../video/omap2/displays/panel-sharp-ls037v7dw01.c |    1 +
 drivers/video/omap2/displays/panel-taal.c          |    2 +
 drivers/video/riva/fbdev.c                         |    1 +
 include/linux/backlight.h                          |    9 +++++++
 60 files changed, 111 insertions(+), 1 deletions(-)

diff --git a/Documentation/ABI/stable/sysfs-class-backlight b/Documentation/ABI/stable/sysfs-class-backlight
index 4d637e1..70302f3 100644
--- a/Documentation/ABI/stable/sysfs-class-backlight
+++ b/Documentation/ABI/stable/sysfs-class-backlight
@@ -34,3 +34,23 @@ Contact:	Richard Purdie <rpurdie@rpsys.net>
 Description:
 		Maximum brightness for <backlight>.
 Users:		HAL
+
+What:		/sys/class/backlight/<backlight>/type
+Date:		September 2010
+KernelVersion:	2.6.37
+Contact:	Matthew Garrett <mjg@redhat.com>
+Description:
+		The type of interface controlled by <backlight>.
+		"firmware": The driver uses a standard firmware interface
+		"platform": The driver uses a platform-specific interface
+		"raw": The driver controls hardware registers directly
+
+		In the general case, when multiple backlight
+		interfaces are available for a single device, firmware
+		control should be preferred to platform control should
+		be preferred to raw control. Using a firmware
+		interface reduces the probability of confusion with
+		the hardware and the OS independently updating the
+		backlight state. Platform interfaces are mostly a
+		holdover from pre-standardisation of firmware
+		interfaces.
diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index 90f8f76..a9eec8c 100644
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -795,6 +795,7 @@ static void acpi_video_device_find_cap(struct acpi_video_device *device)
 		count++;
 
 		memset(&props, 0, sizeof(struct backlight_properties));
+		props.type = BACKLIGHT_FIRMWARE;
 		props.max_brightness = device->brightness->count - 3;
 		device->backlight = backlight_device_register(name, NULL, device,
 							      &acpi_backlight_ops,
diff --git a/drivers/gpu/drm/nouveau/nouveau_backlight.c b/drivers/gpu/drm/nouveau/nouveau_backlight.c
index d3a9c6e..18d7bcc 100644
--- a/drivers/gpu/drm/nouveau/nouveau_backlight.c
+++ b/drivers/gpu/drm/nouveau/nouveau_backlight.c
@@ -98,6 +98,7 @@ static int nouveau_nv40_backlight_init(struct drm_device *dev)
 		return 0;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = 31;
 	bd = backlight_device_register("nv_backlight", &dev->pdev->dev, dev,
 				       &nv40_bl_ops, &props);
@@ -121,6 +122,7 @@ static int nouveau_nv50_backlight_init(struct drm_device *dev)
 		return 0;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = 1025;
 	bd = backlight_device_register("nv_backlight", &dev->pdev->dev, dev,
 				       &nv50_bl_ops, &props);
diff --git a/drivers/hid/hid-picolcd.c b/drivers/hid/hid-picolcd.c
index de9cf21b..657da5a 100644
--- a/drivers/hid/hid-picolcd.c
+++ b/drivers/hid/hid-picolcd.c
@@ -944,6 +944,7 @@ static int picolcd_init_backlight(struct picolcd_data *data, struct hid_report *
 	}
 
 	memset(&props, 0, sizeof(props));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = 0xff;
 	bdev = backlight_device_register(dev_name(dev), dev, data,
 			&picolcd_blops, &props);
diff --git a/drivers/macintosh/via-pmu-backlight.c b/drivers/macintosh/via-pmu-backlight.c
index ade1e65..b1d9117 100644
--- a/drivers/macintosh/via-pmu-backlight.c
+++ b/drivers/macintosh/via-pmu-backlight.c
@@ -163,6 +163,7 @@ void __init pmu_backlight_init()
 	snprintf(name, sizeof(name), "pmubl");
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_PLATFORM;
 	props.max_brightness = FB_BACKLIGHT_LEVELS - 1;
 	bd = backlight_device_register(name, NULL, NULL, &pmu_backlight_data,
 				       &props);
diff --git a/drivers/platform/x86/acer-wmi.c b/drivers/platform/x86/acer-wmi.c
index c5c4b8c..3644c49 100644
--- a/drivers/platform/x86/acer-wmi.c
+++ b/drivers/platform/x86/acer-wmi.c
@@ -1032,6 +1032,7 @@ static int __devinit acer_backlight_init(struct device *dev)
 	struct backlight_device *bd;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_PLATFORM;
 	props.max_brightness = max_brightness;
 	bd = backlight_device_register("acer-wmi", dev, NULL, &acer_bl_ops,
 				       &props);
diff --git a/drivers/platform/x86/asus-laptop.c b/drivers/platform/x86/asus-laptop.c
index f3aa6a7..5a6f7d7 100644
--- a/drivers/platform/x86/asus-laptop.c
+++ b/drivers/platform/x86/asus-laptop.c
@@ -667,6 +667,7 @@ static int asus_backlight_init(struct asus_laptop *asus)
 
 	memset(&props, 0, sizeof(struct backlight_properties));
 	props.max_brightness = 15;
+	props.type = BACKLIGHT_PLATFORM;
 
 	bd = backlight_device_register(ASUS_LAPTOP_FILE,
 				       &asus->platform_device->dev, asus,
diff --git a/drivers/platform/x86/asus_acpi.c b/drivers/platform/x86/asus_acpi.c
index 4633fd8..3be3380 100644
--- a/drivers/platform/x86/asus_acpi.c
+++ b/drivers/platform/x86/asus_acpi.c
@@ -1513,6 +1513,7 @@ static int __init asus_acpi_init(void)
 	}
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_PLATFORM;
 	props.max_brightness = 15;
 	asus_backlight_device = backlight_device_register("asus", NULL, NULL,
 							  &asus_backlight_data,
diff --git a/drivers/platform/x86/classmate-laptop.c b/drivers/platform/x86/classmate-laptop.c
index 9111354..94f93b6 100644
--- a/drivers/platform/x86/classmate-laptop.c
+++ b/drivers/platform/x86/classmate-laptop.c
@@ -564,6 +564,7 @@ static int cmpc_ipml_add(struct acpi_device *acpi)
 		return -ENOMEM;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_PLATFORM;
 	props.max_brightness = 7;
 	ipml->bd = backlight_device_register("cmpc_bl", &acpi->dev,
 					     acpi->handle, &cmpc_bl_ops,
diff --git a/drivers/platform/x86/compal-laptop.c b/drivers/platform/x86/compal-laptop.c
index 034572b..eb95878 100644
--- a/drivers/platform/x86/compal-laptop.c
+++ b/drivers/platform/x86/compal-laptop.c
@@ -970,6 +970,7 @@ static int __init compal_init(void)
 	if (!acpi_video_backlight_support()) {
 		struct backlight_properties props;
 		memset(&props, 0, sizeof(struct backlight_properties));
+		props.type = BACKLIGHT_PLATFORM;
 		props.max_brightness = BACKLIGHT_LEVEL_MAX;
 		compalbl_device = backlight_device_register(DRIVER_NAME,
 							    NULL, NULL,
diff --git a/drivers/platform/x86/dell-laptop.c b/drivers/platform/x86/dell-laptop.c
index 34657f9..fdfb9e7 100644
--- a/drivers/platform/x86/dell-laptop.c
+++ b/drivers/platform/x86/dell-laptop.c
@@ -651,6 +651,7 @@ static int __init dell_init(void)
 	if (max_intensity) {
 		struct backlight_properties props;
 		memset(&props, 0, sizeof(struct backlight_properties));
+		props.type = BACKLIGHT_PLATFORM;
 		props.max_brightness = max_intensity;
 		dell_backlight_device = backlight_device_register("dell_backlight",
 								  &platform_device->dev,
diff --git a/drivers/platform/x86/eeepc-laptop.c b/drivers/platform/x86/eeepc-laptop.c
index 49d9ad7..6605bea 100644
--- a/drivers/platform/x86/eeepc-laptop.c
+++ b/drivers/platform/x86/eeepc-laptop.c
@@ -1147,6 +1147,7 @@ static int eeepc_backlight_init(struct eeepc_laptop *eeepc)
 	struct backlight_device *bd;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_PLATFORM;
 	props.max_brightness = 15;
 	bd = backlight_device_register(EEEPC_LAPTOP_FILE,
 				       &eeepc->platform_device->dev, eeepc,
diff --git a/drivers/platform/x86/eeepc-wmi.c b/drivers/platform/x86/eeepc-wmi.c
index 4d38f98..a304e5a 100644
--- a/drivers/platform/x86/eeepc-wmi.c
+++ b/drivers/platform/x86/eeepc-wmi.c
@@ -518,6 +518,7 @@ static int eeepc_wmi_backlight_init(struct eeepc_wmi *eeepc)
 
 	memset(&props, 0, sizeof(struct backlight_properties));
 	props.max_brightness = 15;
+	props.type = BACKLIGHT_PLATFORM;
 	bd = backlight_device_register(EEEPC_WMI_FILE,
 				       &eeepc->platform_device->dev, eeepc,
 				       &eeepc_wmi_bl_ops, &props);
diff --git a/drivers/platform/x86/fujitsu-laptop.c b/drivers/platform/x86/fujitsu-laptop.c
index 95e3b09..493054c 100644
--- a/drivers/platform/x86/fujitsu-laptop.c
+++ b/drivers/platform/x86/fujitsu-laptop.c
@@ -1128,6 +1128,7 @@ static int __init fujitsu_init(void)
 
 		memset(&props, 0, sizeof(struct backlight_properties));
 		max_brightness = fujitsu->max_brightness;
+		props.type = BACKLIGHT_PLATFORM;
 		props.max_brightness = max_brightness - 1;
 		fujitsu->bl_device = backlight_device_register("fujitsu-laptop",
 							       NULL, NULL,
diff --git a/drivers/platform/x86/msi-laptop.c b/drivers/platform/x86/msi-laptop.c
index 7e9bb6d..142d385 100644
--- a/drivers/platform/x86/msi-laptop.c
+++ b/drivers/platform/x86/msi-laptop.c
@@ -804,6 +804,7 @@ static int __init msi_init(void)
 	} else {
 		struct backlight_properties props;
 		memset(&props, 0, sizeof(struct backlight_properties));
+		props.type = BACKLIGHT_PLATFORM;
 		props.max_brightness = MSI_LCD_LEVEL_MAX - 1;
 		msibl_device = backlight_device_register("msi-laptop-bl", NULL,
 							 NULL, &msibl_ops,
diff --git a/drivers/platform/x86/msi-wmi.c b/drivers/platform/x86/msi-wmi.c
index 35278ad..d5419c9 100644
--- a/drivers/platform/x86/msi-wmi.c
+++ b/drivers/platform/x86/msi-wmi.c
@@ -254,6 +254,7 @@ static int __init msi_wmi_init(void)
 	if (!acpi_video_backlight_support()) {
 		struct backlight_properties props;
 		memset(&props, 0, sizeof(struct backlight_properties));
+		props.type = BACKLIGHT_PLATFORM;
 		props.max_brightness = ARRAY_SIZE(backlight_map) - 1;
 		backlight = backlight_device_register(DRV_NAME, NULL, NULL,
 						      &msi_backlight_ops,
diff --git a/drivers/platform/x86/panasonic-laptop.c b/drivers/platform/x86/panasonic-laptop.c
index cc1e0ba..05be30e 100644
--- a/drivers/platform/x86/panasonic-laptop.c
+++ b/drivers/platform/x86/panasonic-laptop.c
@@ -602,6 +602,7 @@ static int acpi_pcc_hotkey_add(struct acpi_device *device)
 	}
 	/* initialize backlight */
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_PLATFORM;
 	props.max_brightness = pcc->sinf[SINF_AC_MAX_BRIGHT];
 	pcc->backlight = backlight_device_register("panasonic", NULL, pcc,
 						   &pcc_backlight_ops, &props);
diff --git a/drivers/platform/x86/sony-laptop.c b/drivers/platform/x86/sony-laptop.c
index 5e83370..75a1de3 100644
--- a/drivers/platform/x86/sony-laptop.c
+++ b/drivers/platform/x86/sony-laptop.c
@@ -1307,6 +1307,7 @@ static int sony_nc_add(struct acpi_device *device)
 						&handle))) {
 							struct backlight_properties props;
 		memset(&props, 0, sizeof(struct backlight_properties));
+		props.type = BACKLIGHT_PLATFORM;
 		props.max_brightness = SONY_MAX_BRIGHTNESS - 1;
 		sony_backlight_device = backlight_device_register("sony", NULL,
 								  NULL,
diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
index dd59958..d5e6969 100644
--- a/drivers/platform/x86/thinkpad_acpi.c
+++ b/drivers/platform/x86/thinkpad_acpi.c
@@ -6311,6 +6311,7 @@ static int __init brightness_init(struct ibm_init_struct *iibm)
 		return 1;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_PLATFORM;
 	props.max_brightness = bright_maxlvl;
 	props.brightness = b & TP_EC_BACKLIGHT_LVLMSK;
 	ibm_backlight_device = backlight_device_register(TPACPI_BACKLIGHT_DEV_NAME,
diff --git a/drivers/platform/x86/toshiba_acpi.c b/drivers/platform/x86/toshiba_acpi.c
index 209cced..63f42a2 100644
--- a/drivers/platform/x86/toshiba_acpi.c
+++ b/drivers/platform/x86/toshiba_acpi.c
@@ -1018,6 +1018,7 @@ static int __init toshiba_acpi_init(void)
 		create_toshiba_proc_entries();
 	}
 
+	props.type = BACKLIGHT_PLATFORM;
 	props.max_brightness = HCI_LCD_BRIGHTNESS_LEVELS - 1;
 	toshiba_backlight_device = backlight_device_register("toshiba",
 							     &toshiba_acpi.p_dev->dev,
diff --git a/drivers/staging/olpc_dcon/olpc_dcon.c b/drivers/staging/olpc_dcon/olpc_dcon.c
index 9f26dc9..fd9f24b 100644
--- a/drivers/staging/olpc_dcon/olpc_dcon.c
+++ b/drivers/staging/olpc_dcon/olpc_dcon.c
@@ -716,6 +716,7 @@ static int dcon_probe(struct i2c_client *client, const struct i2c_device_id *id)
 	}
 	else {
 		dcon_bl_dev->props.max_brightness = 15;
+		dcon_bl_dev->props.type = BACKLIGHT_RAW;
 		dcon_bl_dev->props.power = FB_BLANK_UNBLANK;
 		dcon_bl_dev->props.brightness = dcon_get_backlight();
 
diff --git a/drivers/staging/samsung-laptop/samsung-laptop.c b/drivers/staging/samsung-laptop/samsung-laptop.c
index 701e8d5..532a48f 100644
--- a/drivers/staging/samsung-laptop/samsung-laptop.c
+++ b/drivers/staging/samsung-laptop/samsung-laptop.c
@@ -488,6 +488,7 @@ static int __init samsung_init(void)
 
 	/* create a backlight device to talk to this one */
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_PLATFORM;
 	props.max_brightness = MAX_BRIGHT;
 	backlight_device = backlight_device_register("samsung", &sdev->dev,
 						     NULL, &backlight_ops,
diff --git a/drivers/usb/misc/appledisplay.c b/drivers/usb/misc/appledisplay.c
index 1fa6ce3..68ab460 100644
--- a/drivers/usb/misc/appledisplay.c
+++ b/drivers/usb/misc/appledisplay.c
@@ -282,6 +282,7 @@ static int appledisplay_probe(struct usb_interface *iface,
 	snprintf(bl_name, sizeof(bl_name), "appledisplay%d",
 		atomic_inc_return(&count_displays) - 1);
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = 0xff;
 	pdata->bd = backlight_device_register(bl_name, NULL, pdata,
 					      &appledisplay_bl_data, &props);
diff --git a/drivers/video/atmel_lcdfb.c b/drivers/video/atmel_lcdfb.c
index bac16345..4b4e8da 100644
--- a/drivers/video/atmel_lcdfb.c
+++ b/drivers/video/atmel_lcdfb.c
@@ -127,6 +127,7 @@ static void init_backlight(struct atmel_lcdfb_info *sinfo)
 		return;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = 0xff;
 	bl = backlight_device_register("backlight", &sinfo->pdev->dev, sinfo,
 				       &atmel_lcdc_bl_ops, &props);
diff --git a/drivers/video/aty/aty128fb.c b/drivers/video/aty/aty128fb.c
index dd9de2e..3813c7a 100644
--- a/drivers/video/aty/aty128fb.c
+++ b/drivers/video/aty/aty128fb.c
@@ -1818,6 +1818,7 @@ static void aty128_bl_init(struct aty128fb_par *par)
 	snprintf(name, sizeof(name), "aty128bl%d", info->node);
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = FB_BACKLIGHT_LEVELS - 1;
 	bd = backlight_device_register(name, info->dev, par, &aty128_bl_data,
 				       &props);
diff --git a/drivers/video/aty/atyfb_base.c b/drivers/video/aty/atyfb_base.c
index 767ab4f..58deaeb 100644
--- a/drivers/video/aty/atyfb_base.c
+++ b/drivers/video/aty/atyfb_base.c
@@ -2241,6 +2241,7 @@ static void aty_bl_init(struct atyfb_par *par)
 	snprintf(name, sizeof(name), "atybl%d", info->node);
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = FB_BACKLIGHT_LEVELS - 1;
 	bd = backlight_device_register(name, info->dev, par, &aty_bl_data,
 				       &props);
diff --git a/drivers/video/aty/radeon_backlight.c b/drivers/video/aty/radeon_backlight.c
index 9b811dd..db572df 100644
--- a/drivers/video/aty/radeon_backlight.c
+++ b/drivers/video/aty/radeon_backlight.c
@@ -158,6 +158,7 @@ void radeonfb_bl_init(struct radeonfb_info *rinfo)
 	snprintf(name, sizeof(name), "radeonbl%d", rinfo->info->node);
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = FB_BACKLIGHT_LEVELS - 1;
 	bd = backlight_device_register(name, rinfo->info->dev, pdata,
 				       &radeon_bl_data, &props);
diff --git a/drivers/video/backlight/88pm860x_bl.c b/drivers/video/backlight/88pm860x_bl.c
index c789c46..a2da3a6 100644
--- a/drivers/video/backlight/88pm860x_bl.c
+++ b/drivers/video/backlight/88pm860x_bl.c
@@ -227,6 +227,7 @@ static int pm860x_backlight_probe(struct platform_device *pdev)
 	}
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = MAX_BRIGHTNESS;
 	bl = backlight_device_register(name, &pdev->dev, data,
 					&pm860x_backlight_ops, &props);
diff --git a/drivers/video/backlight/adp5520_bl.c b/drivers/video/backlight/adp5520_bl.c
index 9f436e0..af31197 100644
--- a/drivers/video/backlight/adp5520_bl.c
+++ b/drivers/video/backlight/adp5520_bl.c
@@ -303,6 +303,7 @@ static int __devinit adp5520_bl_probe(struct platform_device *pdev)
 	mutex_init(&data->lock);
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = ADP5020_MAX_BRIGHTNESS;
 	bl = backlight_device_register(pdev->name, data->master, data,
 				       &adp5520_bl_ops, &props);
diff --git a/drivers/video/backlight/adp8860_bl.c b/drivers/video/backlight/adp8860_bl.c
index 734c650..d2a96a4 100644
--- a/drivers/video/backlight/adp8860_bl.c
+++ b/drivers/video/backlight/adp8860_bl.c
@@ -709,6 +709,7 @@ static int __devinit adp8860_probe(struct i2c_client *client,
 	i2c_set_clientdata(client, data);
 
 	memset(&props, 0, sizeof(props));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = ADP8860_MAX_BRIGHTNESS;
 
 	mutex_init(&data->lock);
diff --git a/drivers/video/backlight/adx_bl.c b/drivers/video/backlight/adx_bl.c
index fe9af12..c861c41 100644
--- a/drivers/video/backlight/adx_bl.c
+++ b/drivers/video/backlight/adx_bl.c
@@ -104,6 +104,7 @@ static int __devinit adx_backlight_probe(struct platform_device *pdev)
 	}
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = 0xff;
 	bldev = backlight_device_register(dev_name(&pdev->dev), &pdev->dev,
 					  bl, &adx_backlight_ops, &props);
diff --git a/drivers/video/backlight/atmel-pwm-bl.c b/drivers/video/backlight/atmel-pwm-bl.c
index e6a66da..0443a4f 100644
--- a/drivers/video/backlight/atmel-pwm-bl.c
+++ b/drivers/video/backlight/atmel-pwm-bl.c
@@ -168,6 +168,7 @@ static int atmel_pwm_bl_probe(struct platform_device *pdev)
 	}
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = pdata->pwm_duty_max - pdata->pwm_duty_min;
 	bldev = backlight_device_register("atmel-pwm-bl", &pdev->dev, pwmbl,
 					  &atmel_pwm_bl_ops, &props);
diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
index 0870329..80d292f 100644
--- a/drivers/video/backlight/backlight.c
+++ b/drivers/video/backlight/backlight.c
@@ -19,6 +19,12 @@
 #include <asm/backlight.h>
 #endif
 
+static const char const *backlight_types[] = {
+	[BACKLIGHT_RAW] = "raw",
+	[BACKLIGHT_PLATFORM] = "platform",
+	[BACKLIGHT_FIRMWARE] = "firmware",
+};
+
 #if defined(CONFIG_FB) || (defined(CONFIG_FB_MODULE) && \
 			   defined(CONFIG_BACKLIGHT_CLASS_DEVICE_MODULE))
 /* This callback gets called when something important happens inside a
@@ -169,6 +175,14 @@ static ssize_t backlight_store_brightness(struct device *dev,
 	return rc;
 }
 
+static ssize_t backlight_show_type(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct backlight_device *bd = to_backlight_device(dev);
+
+	return sprintf(buf, "%s\n", backlight_types[bd->props.type]);
+}
+
 static ssize_t backlight_show_max_brightness(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
@@ -234,6 +248,7 @@ static struct device_attribute bl_device_attributes[] = {
 	__ATTR(actual_brightness, 0444, backlight_show_actual_brightness,
 		     NULL),
 	__ATTR(max_brightness, 0444, backlight_show_max_brightness, NULL),
+	__ATTR(type, 0444, backlight_show_type, NULL),
 	__ATTR_NULL,
 };
 
@@ -292,9 +307,16 @@ struct backlight_device *backlight_device_register(const char *name,
 	dev_set_drvdata(&new_bd->dev, devdata);
 
 	/* Set default properties */
-	if (props)
+	if (props) {
 		memcpy(&new_bd->props, props,
 		       sizeof(struct backlight_properties));
+		if (props->type <= 0 || props->type >= BACKLIGHT_TYPE_MAX) {
+			WARN(1, "%s: invalid backlight type", name);
+			new_bd->props.type = BACKLIGHT_RAW;
+		}
+	} else {
+		new_bd->props.type = BACKLIGHT_RAW;
+	}
 
 	rc = device_register(&new_bd->dev);
 	if (rc) {
diff --git a/drivers/video/backlight/corgi_lcd.c b/drivers/video/backlight/corgi_lcd.c
index 1e71c35..af60983 100644
--- a/drivers/video/backlight/corgi_lcd.c
+++ b/drivers/video/backlight/corgi_lcd.c
@@ -562,6 +562,7 @@ static int __devinit corgi_lcd_probe(struct spi_device *spi)
 	lcd->mode = (pdata) ? pdata->init_mode : CORGI_LCD_MODE_VGA;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = pdata->max_intensity;
 	lcd->bl_dev = backlight_device_register("corgi_bl", &spi->dev, lcd,
 						&corgi_bl_ops, &props);
diff --git a/drivers/video/backlight/cr_bllcd.c b/drivers/video/backlight/cr_bllcd.c
index 397d15e..6c8c540 100644
--- a/drivers/video/backlight/cr_bllcd.c
+++ b/drivers/video/backlight/cr_bllcd.c
@@ -193,6 +193,7 @@ static int cr_backlight_probe(struct platform_device *pdev)
 	}
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	bdp = backlight_device_register("cr-backlight", &pdev->dev, NULL,
 					&cr_backlight_ops, &props);
 	if (IS_ERR(bdp)) {
diff --git a/drivers/video/backlight/da903x_bl.c b/drivers/video/backlight/da903x_bl.c
index 87659ed..62043f1 100644
--- a/drivers/video/backlight/da903x_bl.c
+++ b/drivers/video/backlight/da903x_bl.c
@@ -136,6 +136,7 @@ static int da903x_backlight_probe(struct platform_device *pdev)
 		da903x_write(data->da903x_dev, DA9034_WLED_CONTROL2,
 				DA9034_WLED_ISET(pdata->output_current));
 
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = max_brightness;
 	bl = backlight_device_register(pdev->name, data->da903x_dev, data,
 				       &da903x_backlight_ops, &props);
diff --git a/drivers/video/backlight/ep93xx_bl.c b/drivers/video/backlight/ep93xx_bl.c
index b0cc491..9f1e389 100644
--- a/drivers/video/backlight/ep93xx_bl.c
+++ b/drivers/video/backlight/ep93xx_bl.c
@@ -87,6 +87,7 @@ static int __init ep93xxbl_probe(struct platform_device *dev)
 	ep93xxbl->mmio = EP93XX_RASTER_BRIGHTNESS;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = EP93XX_MAX_BRIGHT;
 	bl = backlight_device_register(dev->name, &dev->dev, ep93xxbl,
 				       &ep93xxbl_ops, &props);
diff --git a/drivers/video/backlight/generic_bl.c b/drivers/video/backlight/generic_bl.c
index 312ca61..8c6befd 100644
--- a/drivers/video/backlight/generic_bl.c
+++ b/drivers/video/backlight/generic_bl.c
@@ -91,6 +91,7 @@ static int genericbl_probe(struct platform_device *pdev)
 		name = machinfo->name;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = machinfo->max_intensity;
 	bd = backlight_device_register(name, &pdev->dev, NULL, &genericbl_ops,
 				       &props);
diff --git a/drivers/video/backlight/hp680_bl.c b/drivers/video/backlight/hp680_bl.c
index 267d23f..38aa002 100644
--- a/drivers/video/backlight/hp680_bl.c
+++ b/drivers/video/backlight/hp680_bl.c
@@ -109,6 +109,7 @@ static int __devinit hp680bl_probe(struct platform_device *pdev)
 	struct backlight_device *bd;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = HP680_MAX_INTENSITY;
 	bd = backlight_device_register("hp680-bl", &pdev->dev, NULL,
 				       &hp680bl_ops, &props);
diff --git a/drivers/video/backlight/jornada720_bl.c b/drivers/video/backlight/jornada720_bl.c
index 2f177b3..40e4fa8 100644
--- a/drivers/video/backlight/jornada720_bl.c
+++ b/drivers/video/backlight/jornada720_bl.c
@@ -106,6 +106,7 @@ static int jornada_bl_probe(struct platform_device *pdev)
 	struct backlight_device *bd;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = BL_MAX_BRIGHT;
 	bd = backlight_device_register(S1D_DEVICENAME, &pdev->dev, NULL,
 				       &jornada_bl_ops, &props);
diff --git a/drivers/video/backlight/kb3886_bl.c b/drivers/video/backlight/kb3886_bl.c
index f439a86..72dd555 100644
--- a/drivers/video/backlight/kb3886_bl.c
+++ b/drivers/video/backlight/kb3886_bl.c
@@ -149,6 +149,7 @@ static int kb3886bl_probe(struct platform_device *pdev)
 		machinfo->limit_mask = -1;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = machinfo->max_intensity;
 	kb3886_backlight_device = backlight_device_register("kb3886-bl",
 							    &pdev->dev, NULL,
diff --git a/drivers/video/backlight/locomolcd.c b/drivers/video/backlight/locomolcd.c
index d2f5901..bbca312 100644
--- a/drivers/video/backlight/locomolcd.c
+++ b/drivers/video/backlight/locomolcd.c
@@ -184,6 +184,7 @@ static int locomolcd_probe(struct locomo_dev *ldev)
 	local_irq_restore(flags);
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = 4;
 	locomolcd_bl_device = backlight_device_register("locomo-bl",
 							&ldev->dev, NULL,
diff --git a/drivers/video/backlight/max8925_bl.c b/drivers/video/backlight/max8925_bl.c
index 209acc1..07e8e27 100644
--- a/drivers/video/backlight/max8925_bl.c
+++ b/drivers/video/backlight/max8925_bl.c
@@ -136,6 +136,7 @@ static int __devinit max8925_backlight_probe(struct platform_device *pdev)
 	data->current_brightness = 0;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = MAX_BRIGHTNESS;
 	bl = backlight_device_register(name, &pdev->dev, data,
 					&max8925_backlight_ops, &props);
diff --git a/drivers/video/backlight/mbp_nvidia_bl.c b/drivers/video/backlight/mbp_nvidia_bl.c
index 1485f73..74c3394 100644
--- a/drivers/video/backlight/mbp_nvidia_bl.c
+++ b/drivers/video/backlight/mbp_nvidia_bl.c
@@ -367,6 +367,7 @@ static int __init mbp_init(void)
 		return -ENXIO;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_PLATFORM;
 	props.max_brightness = 15;
 	mbp_backlight_device = backlight_device_register("mbp_backlight", NULL,
 							 NULL,
diff --git a/drivers/video/backlight/omap1_bl.c b/drivers/video/backlight/omap1_bl.c
index d3bc562..08d26a7 100644
--- a/drivers/video/backlight/omap1_bl.c
+++ b/drivers/video/backlight/omap1_bl.c
@@ -146,6 +146,7 @@ static int omapbl_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = OMAPBL_MAX_INTENSITY;
 	dev = backlight_device_register("omap-bl", &pdev->dev, bl, &omapbl_ops,
 					&props);
diff --git a/drivers/video/backlight/pcf50633-backlight.c b/drivers/video/backlight/pcf50633-backlight.c
index 3c424f7..ef5628d 100644
--- a/drivers/video/backlight/pcf50633-backlight.c
+++ b/drivers/video/backlight/pcf50633-backlight.c
@@ -112,6 +112,7 @@ static int __devinit pcf50633_bl_probe(struct platform_device *pdev)
 	if (!pcf_bl)
 		return -ENOMEM;
 
+	bl_props.type = BACKLIGHT_RAW;
 	bl_props.max_brightness = 0x3f;
 	bl_props.power = FB_BLANK_UNBLANK;
 
diff --git a/drivers/video/backlight/progear_bl.c b/drivers/video/backlight/progear_bl.c
index 809278c..6af183d 100644
--- a/drivers/video/backlight/progear_bl.c
+++ b/drivers/video/backlight/progear_bl.c
@@ -84,6 +84,7 @@ static int progearbl_probe(struct platform_device *pdev)
 	pci_write_config_byte(sb_dev, SB_MPS1, temp | 0x20);
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = HW_LEVEL_MAX - HW_LEVEL_MIN;
 	progear_backlight_device = backlight_device_register("progear-bl",
 							     &pdev->dev, NULL,
diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index 21866ec..2c2a2c7 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -108,6 +108,7 @@ static int pwm_backlight_probe(struct platform_device *pdev)
 		dev_dbg(&pdev->dev, "got pwm for backlight\n");
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = data->max_brightness;
 	bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, pb,
 				       &pwm_backlight_ops, &props);
diff --git a/drivers/video/backlight/s6e63m0.c b/drivers/video/backlight/s6e63m0.c
index 5927db0..322040f 100644
--- a/drivers/video/backlight/s6e63m0.c
+++ b/drivers/video/backlight/s6e63m0.c
@@ -778,6 +778,7 @@ static int __devinit s6e63m0_probe(struct spi_device *spi)
 
 	bd->props.max_brightness = MAX_BRIGHTNESS;
 	bd->props.brightness = MAX_BRIGHTNESS;
+	bd->props.type = BACKLIGHT_RAW;
 	lcd->bd = bd;
 
 	/*
diff --git a/drivers/video/backlight/tosa_bl.c b/drivers/video/backlight/tosa_bl.c
index 2a04b38..425a736 100644
--- a/drivers/video/backlight/tosa_bl.c
+++ b/drivers/video/backlight/tosa_bl.c
@@ -102,6 +102,7 @@ static int __devinit tosa_bl_probe(struct i2c_client *client,
 	data->i2c = client;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = 512 - 1;
 	data->bl = backlight_device_register("tosa-bl", &client->dev, data,
 					     &bl_ops, &props);
diff --git a/drivers/video/backlight/wm831x_bl.c b/drivers/video/backlight/wm831x_bl.c
index 08fd87f..d4c6eb2 100644
--- a/drivers/video/backlight/wm831x_bl.c
+++ b/drivers/video/backlight/wm831x_bl.c
@@ -193,6 +193,7 @@ static int wm831x_backlight_probe(struct platform_device *pdev)
 	data->current_brightness = 0;
 	data->isink_reg = isink_reg;
 
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = max_isel;
 	bl = backlight_device_register("wm831x", &pdev->dev, data,
 				       &wm831x_backlight_ops, &props);
diff --git a/drivers/video/bf54x-lq043fb.c b/drivers/video/bf54x-lq043fb.c
index e7d0f52..2464b91 100644
--- a/drivers/video/bf54x-lq043fb.c
+++ b/drivers/video/bf54x-lq043fb.c
@@ -649,6 +649,7 @@ static int __devinit bfin_bf54x_probe(struct platform_device *pdev)
 	}
 #ifndef NO_BL_SUPPORT
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = 255;
 	bl_dev = backlight_device_register("bf54x-bl", NULL, NULL,
 					   &bfin_lq043fb_bl_ops, &props);
diff --git a/drivers/video/bfin-t350mcqb-fb.c b/drivers/video/bfin-t350mcqb-fb.c
index 3cf7767..d8de29f 100644
--- a/drivers/video/bfin-t350mcqb-fb.c
+++ b/drivers/video/bfin-t350mcqb-fb.c
@@ -545,6 +545,7 @@ static int __devinit bfin_t350mcqb_probe(struct platform_device *pdev)
 	}
 #ifndef NO_BL_SUPPORT
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = 255;
 	bl_dev = backlight_device_register("bf52x-bl", NULL, NULL,
 					   &bfin_lq043fb_bl_ops, &props);
diff --git a/drivers/video/imxfb.c b/drivers/video/imxfb.c
index 69bd4a5..ef72cb4 100644
--- a/drivers/video/imxfb.c
+++ b/drivers/video/imxfb.c
@@ -499,6 +499,7 @@ static void imxfb_init_backlight(struct imxfb_info *fbi)
 
 	memset(&props, 0, sizeof(struct backlight_properties));
 	props.max_brightness = 0xff;
+	props.type = BACKLIGHT_RAW;
 	writel(fbi->pwmr, fbi->regs + LCDC_PWMR);
 
 	bl = backlight_device_register("imxfb-bl", &fbi->pdev->dev, fbi,
diff --git a/drivers/video/nvidia/nv_backlight.c b/drivers/video/nvidia/nv_backlight.c
index 6aac6d1..8471008 100644
--- a/drivers/video/nvidia/nv_backlight.c
+++ b/drivers/video/nvidia/nv_backlight.c
@@ -111,6 +111,7 @@ void nvidia_bl_init(struct nvidia_par *par)
 	snprintf(name, sizeof(name), "nvidiabl%d", info->node);
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = FB_BACKLIGHT_LEVELS - 1;
 	bd = backlight_device_register(name, info->dev, par, &nvidia_bl_ops,
 				       &props);
diff --git a/drivers/video/omap2/displays/panel-acx565akm.c b/drivers/video/omap2/displays/panel-acx565akm.c
index e773106..7e04c92 100644
--- a/drivers/video/omap2/displays/panel-acx565akm.c
+++ b/drivers/video/omap2/displays/panel-acx565akm.c
@@ -534,6 +534,7 @@ static int acx_panel_probe(struct omap_dss_device *dssdev)
 
 	props.fb_blank = FB_BLANK_UNBLANK;
 	props.power = FB_BLANK_UNBLANK;
+	props.type = BACKLIGHT_RAW;
 
 	bldev = backlight_device_register("acx565akm", &md->spi->dev,
 			md, &acx565akm_bl_ops, &props);
diff --git a/drivers/video/omap2/displays/panel-sharp-ls037v7dw01.c b/drivers/video/omap2/displays/panel-sharp-ls037v7dw01.c
index 9a138f6..d2b35d2 100644
--- a/drivers/video/omap2/displays/panel-sharp-ls037v7dw01.c
+++ b/drivers/video/omap2/displays/panel-sharp-ls037v7dw01.c
@@ -99,6 +99,7 @@ static int sharp_ls_panel_probe(struct omap_dss_device *dssdev)
 
 	memset(&props, 0, sizeof(struct backlight_properties));
 	props.max_brightness = dssdev->max_backlight_level;
+	props.type = BACKLIGHT_RAW;
 
 	bl = backlight_device_register("sharp-ls", &dssdev->dev, dssdev,
 			&sharp_ls_bl_ops, &props);
diff --git a/drivers/video/omap2/displays/panel-taal.c b/drivers/video/omap2/displays/panel-taal.c
index 61026f9..c74e8b7 100644
--- a/drivers/video/omap2/displays/panel-taal.c
+++ b/drivers/video/omap2/displays/panel-taal.c
@@ -729,6 +729,8 @@ static int taal_probe(struct omap_dss_device *dssdev)
 		props.max_brightness = 255;
 	else
 		props.max_brightness = 127;
+
+	props.type = BACKLIGHT_RAW;
 	bldev = backlight_device_register("taal", &dssdev->dev, dssdev,
 					  &taal_bl_ops, &props);
 	if (IS_ERR(bldev)) {
diff --git a/drivers/video/riva/fbdev.c b/drivers/video/riva/fbdev.c
index da38818..d8ab7be 100644
--- a/drivers/video/riva/fbdev.c
+++ b/drivers/video/riva/fbdev.c
@@ -355,6 +355,7 @@ static void riva_bl_init(struct riva_par *par)
 	snprintf(name, sizeof(name), "rivabl%d", info->node);
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = FB_BACKLIGHT_LEVELS - 1;
 	bd = backlight_device_register(name, info->dev, par, &riva_bl_ops,
 				       &props);
diff --git a/include/linux/backlight.h b/include/linux/backlight.h
index 4a3d52e..5ffc6dd 100644
--- a/include/linux/backlight.h
+++ b/include/linux/backlight.h
@@ -32,6 +32,13 @@ enum backlight_update_reason {
 	BACKLIGHT_UPDATE_SYSFS,
 };
 
+enum backlight_type {
+	BACKLIGHT_RAW = 1,
+	BACKLIGHT_PLATFORM,
+	BACKLIGHT_FIRMWARE,
+	BACKLIGHT_TYPE_MAX,
+};
+
 struct backlight_device;
 struct fb_info;
 
@@ -62,6 +69,8 @@ struct backlight_properties {
 	/* FB Blanking active? (values as for power) */
 	/* Due to be removed, please use (state & BL_CORE_FBBLANK) */
 	int fb_blank;
+	/* Backlight type */
+	enum backlight_type type;
 	/* Flags used to signal drivers of state changes */
 	/* Upper 4 bits are reserved for driver internal use */
 	unsigned int state;
-- 
1.7.3.4

Re: [PATCH 1/5] Backlight: Add backlight type

[Matthew Garrett]

On Mon, Nov 22, 2010 at 01:35:48PM +0000, Richard Purdie wrote:

> Its the reverse situation I worry about. Are there situations where
> there are multiple connectors on the PCI device and the ACPI interface
> just controls one of them but controls for the other connectors may
> exist?

Yes, that's certainly possible and it'd be desirable to fix this up, but 
the same problem also applies to platform interfaces and it's typically 
unfixable there. My userspace implementation looks at the connector type 
to determine the best approach - if it's not LVDS or eDP it ignores the 
firmware and platform interfaces, so you'll fall back to the raw 
interface if it can provide support for your connector (presumably via 
ddcci, although we don't have this implemented yet)

-- 
Matthew Garrett | mjg59@srcf.ucam.org

Re: [PATCH 1/5] Backlight: Add backlight type

[Richard Purdie]

On Mon, 2010-11-22 at 12:30 +0000, Matthew Garrett wrote:
> On Mon, Nov 22, 2010 at 10:17:00AM +0000, Richard Purdie wrote:
> 
> > I also want to make sure you think this patch is going to scale with
> > multiple GPU output machines? Thats the main reason I've held off any
> > patch like this as it doesn't help solve that problem as far as I can
> > tell. Yes, we have the device parent information and I see later in the
> > patch series you ensure the backlight is registered against the
> > connector which is good. If you have an ACPI "firmware" control that you
> > say should always be preferred, how do we know which connector device
> > that corresponds to in the multiple output case? From that point of view
> > this model falls apart?
> 
> The ACPI device will point at the correct PCI device. Associating it 
> with the appropriate connector is theoretically possible in the case of 
> open drivers, but I hadn't seen it as a high priority since (in 
> practice) there's no situations where an ACPI interface will be able to 
> control more than one backlight.

Its the reverse situation I worry about. Are there situations where
there are multiple connectors on the PCI device and the ACPI interface
just controls one of them but controls for the other connectors may
exist?

I'm typing this with an external monitor plugged into my laptop with
i915 graphics...

Cheers,

Richard

Re: [PATCH 1/5] Backlight: Add backlight type

[Matthew Garrett]

On Mon, Nov 22, 2010 at 10:17:00AM +0000, Richard Purdie wrote:

> I also want to make sure you think this patch is going to scale with
> multiple GPU output machines? Thats the main reason I've held off any
> patch like this as it doesn't help solve that problem as far as I can
> tell. Yes, we have the device parent information and I see later in the
> patch series you ensure the backlight is registered against the
> connector which is good. If you have an ACPI "firmware" control that you
> say should always be preferred, how do we know which connector device
> that corresponds to in the multiple output case? From that point of view
> this model falls apart?

The ACPI device will point at the correct PCI device. Associating it 
with the appropriate connector is theoretically possible in the case of 
open drivers, but I hadn't seen it as a high priority since (in 
practice) there's no situations where an ACPI interface will be able to 
control more than one backlight.

-- 
Matthew Garrett | mjg59@srcf.ucam.org

Re: [PATCH 1/5] Backlight: Add backlight type

[Richard Purdie]

On Fri, 2010-11-19 at 20:25 +0000, Matthew Garrett wrote:
> On Fri, Nov 19, 2010 at 12:05:23PM -0800, Andrew Morton wrote:
> > On Fri, 19 Nov 2010 10:53:52 -0500
> > Matthew Garrett <mjg@redhat.com> wrote:
> > 
> > > There may be multiple ways of controlling the backlight on a given machine.
> > > Allow drivers to expose the type of interface they are providing, making
> > > it possible for userspace to make appropriate policy decisions.
> > > 
> > > ...
> > >
> > >  60 files changed, 102 insertions(+), 0 deletions(-)
> > 
> > This patch has a pretty short half-life.
> 
> Well, ideally it would have landed in the backlight tree when I sent it 
> months ago. Then we'd have the opportunity to ensure that everything was 
> fixed up before it went in in the merge window.
> 
> > > @@ -62,6 +68,8 @@ struct backlight_properties {
> > >  	/* FB Blanking active? (values as for power) */
> > >  	/* Due to be removed, please use (state & BL_CORE_FBBLANK) */
> > >  	int fb_blank;
> > > +	/* Backlight type */
> > > +	enum backlight_type type;
> > >  	/* Flags used to signal drivers of state changes */
> > >  	/* Upper 4 bits are reserved for driver internal use */
> > >  	unsigned int state;
> > 
> > And if/when the half-life expires, we'll have drivers in-tree which
> > forget to set backlight_properties.type.  I haven't checked, but if
> > we're lucky they will default to "0".
> 
> Depends entirely on whether they kzalloc the structure or not before
> calling backlight_device_register(). 
> 
> > What will be the runtime effects upon such unconverted drivers? 
> > Ideally we'd like them to continue to work OK, and to emit a runtime
> > warning.  In which case you'll need BACKLIGHT_RAW=1 so the unconverted
> > driver can be detected, warned about and fixed up by the core code.
> 
> The worst case I can think of is that we walk off the array - I guess 
> there's an argument for sanity checking that in backlight_show_type().

I think adding a BACKLIGHT_TYPEUNKNOWN as the first item in the enum,
sanity checking the array bounds and printing a warning if type is not
one of the defined values would be good.

I also want to make sure you think this patch is going to scale with
multiple GPU output machines? Thats the main reason I've held off any
patch like this as it doesn't help solve that problem as far as I can
tell. Yes, we have the device parent information and I see later in the
patch series you ensure the backlight is registered against the
connector which is good. If you have an ACPI "firmware" control that you
say should always be preferred, how do we know which connector device
that corresponds to in the multiple output case? From that point of view
this model falls apart?

What I really want to avoid is a new interface which just papers over
cracks, only to have everything crumble anyway.

Cheers,

Richard

Re: [PATCH 1/5] Backlight: Add backlight type

[Andrew Morton]

On Fri, 19 Nov 2010 20:25:59 +0000
Matthew Garrett <mjg59@srcf.ucam.org> wrote:

> On Fri, Nov 19, 2010 at 12:05:23PM -0800, Andrew Morton wrote:
> > On Fri, 19 Nov 2010 10:53:52 -0500
> > Matthew Garrett <mjg@redhat.com> wrote:
> > 
> > > There may be multiple ways of controlling the backlight on a given machine.
> > > Allow drivers to expose the type of interface they are providing, making
> > > it possible for userspace to make appropriate policy decisions.
> > > 
> > > ...
> > >
> > >  60 files changed, 102 insertions(+), 0 deletions(-)
> > 
> > This patch has a pretty short half-life.
> 
> Well, ideally it would have landed in the backlight tree when I sent it 
> months ago. Then we'd have the opportunity to ensure that everything was 
> fixed up before it went in in the merge window.

Richard got distracted.  At present I'm grabbing the leds and backlight
patches and Richard is reviewing them as they fly past.

I don't see there's much point in me merging this patch series so if it
survives review, I'd suggest that you put it into an mjg tree and
thence into linux-next and mainline?

> > > @@ -62,6 +68,8 @@ struct backlight_properties {
> > >  	/* FB Blanking active? (values as for power) */
> > >  	/* Due to be removed, please use (state & BL_CORE_FBBLANK) */
> > >  	int fb_blank;
> > > +	/* Backlight type */
> > > +	enum backlight_type type;
> > >  	/* Flags used to signal drivers of state changes */
> > >  	/* Upper 4 bits are reserved for driver internal use */
> > >  	unsigned int state;
> > 
> > And if/when the half-life expires, we'll have drivers in-tree which
> > forget to set backlight_properties.type.  I haven't checked, but if
> > we're lucky they will default to "0".
> 
> Depends entirely on whether they kzalloc the structure or not before
> calling backlight_device_register(). 

Well.  Even if it's uninitialised, the chances of the value being 1, 2
or 3 for all users are pretty small, so we'll still get to hear about
it if the runtime check is appropriately implemented.

> > What will be the runtime effects upon such unconverted drivers? 
> > Ideally we'd like them to continue to work OK, and to emit a runtime
> > warning.  In which case you'll need BACKLIGHT_RAW=1 so the unconverted
> > driver can be detected, warned about and fixed up by the core code.
> 
> The worst case I can think of is that we walk off the array - I guess 
> there's an argument for sanity checking that in backlight_show_type().

OK, well please have a think about it, see what you can do to handle
unconverted (and possibly out-of-tree) drivers in a friendly fashion.

Re: [PATCH 1/5] Backlight: Add backlight type

[Matthew Garrett]

On Fri, Nov 19, 2010 at 12:05:23PM -0800, Andrew Morton wrote:
> On Fri, 19 Nov 2010 10:53:52 -0500
> Matthew Garrett <mjg@redhat.com> wrote:
> 
> > There may be multiple ways of controlling the backlight on a given machine.
> > Allow drivers to expose the type of interface they are providing, making
> > it possible for userspace to make appropriate policy decisions.
> > 
> > ...
> >
> >  60 files changed, 102 insertions(+), 0 deletions(-)
> 
> This patch has a pretty short half-life.

Well, ideally it would have landed in the backlight tree when I sent it 
months ago. Then we'd have the opportunity to ensure that everything was 
fixed up before it went in in the merge window.

> > @@ -62,6 +68,8 @@ struct backlight_properties {
> >  	/* FB Blanking active? (values as for power) */
> >  	/* Due to be removed, please use (state & BL_CORE_FBBLANK) */
> >  	int fb_blank;
> > +	/* Backlight type */
> > +	enum backlight_type type;
> >  	/* Flags used to signal drivers of state changes */
> >  	/* Upper 4 bits are reserved for driver internal use */
> >  	unsigned int state;
> 
> And if/when the half-life expires, we'll have drivers in-tree which
> forget to set backlight_properties.type.  I haven't checked, but if
> we're lucky they will default to "0".

Depends entirely on whether they kzalloc the structure or not before
calling backlight_device_register(). 

> What will be the runtime effects upon such unconverted drivers? 
> Ideally we'd like them to continue to work OK, and to emit a runtime
> warning.  In which case you'll need BACKLIGHT_RAW=1 so the unconverted
> driver can be detected, warned about and fixed up by the core code.

The worst case I can think of is that we walk off the array - I guess 
there's an argument for sanity checking that in backlight_show_type().

-- 
Matthew Garrett | mjg59@srcf.ucam.org

Re: [PATCH 1/5] Backlight: Add backlight type

[Andrew Morton]

On Fri, 19 Nov 2010 10:53:52 -0500
Matthew Garrett <mjg@redhat.com> wrote:

> There may be multiple ways of controlling the backlight on a given machine.
> Allow drivers to expose the type of interface they are providing, making
> it possible for userspace to make appropriate policy decisions.
> 
> ...
>
>  60 files changed, 102 insertions(+), 0 deletions(-)

This patch has a pretty short half-life.

>
> ...
>
> --- a/include/linux/backlight.h
> +++ b/include/linux/backlight.h
> @@ -32,6 +32,12 @@ enum backlight_update_reason {
>  	BACKLIGHT_UPDATE_SYSFS,
>  };
>  
> +enum backlight_type {
> +	BACKLIGHT_RAW,
> +	BACKLIGHT_PLATFORM,
> +	BACKLIGHT_FIRMWARE,
> +};
> +
>  struct backlight_device;
>  struct fb_info;
>  
> @@ -62,6 +68,8 @@ struct backlight_properties {
>  	/* FB Blanking active? (values as for power) */
>  	/* Due to be removed, please use (state & BL_CORE_FBBLANK) */
>  	int fb_blank;
> +	/* Backlight type */
> +	enum backlight_type type;
>  	/* Flags used to signal drivers of state changes */
>  	/* Upper 4 bits are reserved for driver internal use */
>  	unsigned int state;

And if/when the half-life expires, we'll have drivers in-tree which
forget to set backlight_properties.type.  I haven't checked, but if
we're lucky they will default to "0".

What will be the runtime effects upon such unconverted drivers? 
Ideally we'd like them to continue to work OK, and to emit a runtime
warning.  In which case you'll need BACKLIGHT_RAW=1 so the unconverted
driver can be detected, warned about and fixed up by the core code.

Re: [PATCH 1/5] Backlight: Add backlight type

[Andrew Morton]

On Fri, 19 Nov 2010 10:53:52 -0500
Matthew Garrett <mjg@redhat.com> wrote:

> There may be multiple ways of controlling the backlight on a given machine.
> Allow drivers to expose the type of interface they are providing, making
> it possible for userspace to make appropriate policy decisions.
> 
> ...
>
>  60 files changed, 102 insertions(+), 0 deletions(-)

This patch has a pretty short half-life.

>
> ...
>
> --- a/include/linux/backlight.h
> +++ b/include/linux/backlight.h
> @@ -32,6 +32,12 @@ enum backlight_update_reason {
>  	BACKLIGHT_UPDATE_SYSFS,
>  };
>  
> +enum backlight_type {
> +	BACKLIGHT_RAW,
> +	BACKLIGHT_PLATFORM,
> +	BACKLIGHT_FIRMWARE,
> +};
> +
>  struct backlight_device;
>  struct fb_info;
>  
> @@ -62,6 +68,8 @@ struct backlight_properties {
>  	/* FB Blanking active? (values as for power) */
>  	/* Due to be removed, please use (state & BL_CORE_FBBLANK) */
>  	int fb_blank;
> +	/* Backlight type */
> +	enum backlight_type type;
>  	/* Flags used to signal drivers of state changes */
>  	/* Upper 4 bits are reserved for driver internal use */
>  	unsigned int state;

And if/when the half-life expires, we'll have drivers in-tree which
forget to set backlight_properties.type.  I haven't checked, but if
we're lucky they will default to "0".

What will be the runtime effects upon such unconverted drivers? 
Ideally we'd like them to continue to work OK, and to emit a runtime
warning.  In which case you'll need BACKLIGHT_RAW=1 so the unconverted
driver can be detected, warned about and fixed up by the core code.

[PATCH 1/5] Backlight: Add backlight type

[Matthew Garrett]

There may be multiple ways of controlling the backlight on a given machine.
Allow drivers to expose the type of interface they are providing, making
it possible for userspace to make appropriate policy decisions.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: intel-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
---
 Documentation/ABI/stable/sysfs-class-backlight     |   20 ++++++++++++++++++++
 drivers/acpi/video.c                               |    1 +
 drivers/gpu/drm/nouveau/nouveau_backlight.c        |    2 ++
 drivers/hid/hid-picolcd.c                          |    1 +
 drivers/macintosh/via-pmu-backlight.c              |    1 +
 drivers/platform/x86/acer-wmi.c                    |    1 +
 drivers/platform/x86/asus-laptop.c                 |    1 +
 drivers/platform/x86/asus_acpi.c                   |    1 +
 drivers/platform/x86/classmate-laptop.c            |    1 +
 drivers/platform/x86/compal-laptop.c               |    1 +
 drivers/platform/x86/dell-laptop.c                 |    1 +
 drivers/platform/x86/eeepc-laptop.c                |    1 +
 drivers/platform/x86/eeepc-wmi.c                   |    1 +
 drivers/platform/x86/fujitsu-laptop.c              |    1 +
 drivers/platform/x86/msi-laptop.c                  |    1 +
 drivers/platform/x86/msi-wmi.c                     |    1 +
 drivers/platform/x86/panasonic-laptop.c            |    1 +
 drivers/platform/x86/sony-laptop.c                 |    1 +
 drivers/platform/x86/thinkpad_acpi.c               |    1 +
 drivers/platform/x86/toshiba_acpi.c                |    1 +
 drivers/staging/olpc_dcon/olpc_dcon.c              |    1 +
 drivers/staging/samsung-laptop/samsung-laptop.c    |    1 +
 drivers/usb/misc/appledisplay.c                    |    1 +
 drivers/video/atmel_lcdfb.c                        |    1 +
 drivers/video/aty/aty128fb.c                       |    1 +
 drivers/video/aty/atyfb_base.c                     |    1 +
 drivers/video/aty/radeon_backlight.c               |    1 +
 drivers/video/backlight/88pm860x_bl.c              |    1 +
 drivers/video/backlight/adp5520_bl.c               |    1 +
 drivers/video/backlight/adp8860_bl.c               |    1 +
 drivers/video/backlight/adx_bl.c                   |    1 +
 drivers/video/backlight/atmel-pwm-bl.c             |    1 +
 drivers/video/backlight/backlight.c                |   15 +++++++++++++++
 drivers/video/backlight/corgi_lcd.c                |    1 +
 drivers/video/backlight/cr_bllcd.c                 |    1 +
 drivers/video/backlight/da903x_bl.c                |    1 +
 drivers/video/backlight/ep93xx_bl.c                |    1 +
 drivers/video/backlight/generic_bl.c               |    1 +
 drivers/video/backlight/hp680_bl.c                 |    1 +
 drivers/video/backlight/jornada720_bl.c            |    1 +
 drivers/video/backlight/kb3886_bl.c                |    1 +
 drivers/video/backlight/locomolcd.c                |    1 +
 drivers/video/backlight/max8925_bl.c               |    1 +
 drivers/video/backlight/mbp_nvidia_bl.c            |    1 +
 drivers/video/backlight/omap1_bl.c                 |    1 +
 drivers/video/backlight/pcf50633-backlight.c       |    1 +
 drivers/video/backlight/progear_bl.c               |    1 +
 drivers/video/backlight/pwm_bl.c                   |    1 +
 drivers/video/backlight/s6e63m0.c                  |    1 +
 drivers/video/backlight/tosa_bl.c                  |    1 +
 drivers/video/backlight/wm831x_bl.c                |    1 +
 drivers/video/bf54x-lq043fb.c                      |    1 +
 drivers/video/bfin-t350mcqb-fb.c                   |    1 +
 drivers/video/imxfb.c                              |    1 +
 drivers/video/nvidia/nv_backlight.c                |    1 +
 drivers/video/omap2/displays/panel-acx565akm.c     |    1 +
 .../video/omap2/displays/panel-sharp-ls037v7dw01.c |    1 +
 drivers/video/omap2/displays/panel-taal.c          |    2 ++
 drivers/video/riva/fbdev.c                         |    1 +
 include/linux/backlight.h                          |    8 ++++++++
 60 files changed, 102 insertions(+), 0 deletions(-)

diff --git a/Documentation/ABI/stable/sysfs-class-backlight b/Documentation/ABI/stable/sysfs-class-backlight
index 4d637e1..70302f3 100644
--- a/Documentation/ABI/stable/sysfs-class-backlight
+++ b/Documentation/ABI/stable/sysfs-class-backlight
@@ -34,3 +34,23 @@ Contact:	Richard Purdie <rpurdie@rpsys.net>
 Description:
 		Maximum brightness for <backlight>.
 Users:		HAL
+
+What:		/sys/class/backlight/<backlight>/type
+Date:		September 2010
+KernelVersion:	2.6.37
+Contact:	Matthew Garrett <mjg@redhat.com>
+Description:
+		The type of interface controlled by <backlight>.
+		"firmware": The driver uses a standard firmware interface
+		"platform": The driver uses a platform-specific interface
+		"raw": The driver controls hardware registers directly
+
+		In the general case, when multiple backlight
+		interfaces are available for a single device, firmware
+		control should be preferred to platform control should
+		be preferred to raw control. Using a firmware
+		interface reduces the probability of confusion with
+		the hardware and the OS independently updating the
+		backlight state. Platform interfaces are mostly a
+		holdover from pre-standardisation of firmware
+		interfaces.
diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index 5cd0228..38165a8 100644
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -856,6 +856,7 @@ static void acpi_video_device_find_cap(struct acpi_video_device *device)
 		count++;
 
 		memset(&props, 0, sizeof(struct backlight_properties));
+		props.type = BACKLIGHT_FIRMWARE;
 		props.max_brightness = device->brightness->count - 3;
 		device->backlight = backlight_device_register(name, NULL, device,
 							      &acpi_backlight_ops,
diff --git a/drivers/gpu/drm/nouveau/nouveau_backlight.c b/drivers/gpu/drm/nouveau/nouveau_backlight.c
index 406228f..9485af3 100644
--- a/drivers/gpu/drm/nouveau/nouveau_backlight.c
+++ b/drivers/gpu/drm/nouveau/nouveau_backlight.c
@@ -97,6 +97,7 @@ static int nouveau_nv40_backlight_init(struct drm_device *dev)
 		return 0;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = 31;
 	bd = backlight_device_register("nv_backlight", &dev->pdev->dev, dev,
 				       &nv40_bl_ops, &props);
@@ -120,6 +121,7 @@ static int nouveau_nv50_backlight_init(struct drm_device *dev)
 		return 0;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = 1025;
 	bd = backlight_device_register("nv_backlight", &dev->pdev->dev, dev,
 				       &nv50_bl_ops, &props);
diff --git a/drivers/hid/hid-picolcd.c b/drivers/hid/hid-picolcd.c
index bc2e077..3418b82 100644
--- a/drivers/hid/hid-picolcd.c
+++ b/drivers/hid/hid-picolcd.c
@@ -944,6 +944,7 @@ static int picolcd_init_backlight(struct picolcd_data *data, struct hid_report *
 	}
 
 	memset(&props, 0, sizeof(props));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = 0xff;
 	bdev = backlight_device_register(dev_name(dev), dev, data,
 			&picolcd_blops, &props);
diff --git a/drivers/macintosh/via-pmu-backlight.c b/drivers/macintosh/via-pmu-backlight.c
index 1cec02f..364a295 100644
--- a/drivers/macintosh/via-pmu-backlight.c
+++ b/drivers/macintosh/via-pmu-backlight.c
@@ -163,6 +163,7 @@ void __init pmu_backlight_init()
 	snprintf(name, sizeof(name), "pmubl");
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_PLATFORM;
 	props.max_brightness = FB_BACKLIGHT_LEVELS - 1;
 	bd = backlight_device_register(name, NULL, NULL, &pmu_backlight_data,
 				       &props);
diff --git a/drivers/platform/x86/acer-wmi.c b/drivers/platform/x86/acer-wmi.c
index c8c6537..3d3fcfc 100644
--- a/drivers/platform/x86/acer-wmi.c
+++ b/drivers/platform/x86/acer-wmi.c
@@ -926,6 +926,7 @@ static int __devinit acer_backlight_init(struct device *dev)
 	struct backlight_device *bd;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_PLATFORM;
 	props.max_brightness = max_brightness;
 	bd = backlight_device_register("acer-wmi", dev, NULL, &acer_bl_ops,
 				       &props);
diff --git a/drivers/platform/x86/asus-laptop.c b/drivers/platform/x86/asus-laptop.c
index 60a5a5c..60b0159 100644
--- a/drivers/platform/x86/asus-laptop.c
+++ b/drivers/platform/x86/asus-laptop.c
@@ -648,6 +648,7 @@ static int asus_backlight_init(struct asus_laptop *asus)
 
 	memset(&props, 0, sizeof(struct backlight_properties));
 	props.max_brightness = 15;
+	props.type = BACKLIGHT_PLATFORM;
 
 	bd = backlight_device_register(ASUS_LAPTOP_FILE,
 				       &asus->platform_device->dev, asus,
diff --git a/drivers/platform/x86/asus_acpi.c b/drivers/platform/x86/asus_acpi.c
index ca05aef..3ea8df5 100644
--- a/drivers/platform/x86/asus_acpi.c
+++ b/drivers/platform/x86/asus_acpi.c
@@ -1513,6 +1513,7 @@ static int __init asus_acpi_init(void)
 	}
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_PLATFORM;
 	props.max_brightness = 15;
 	asus_backlight_device = backlight_device_register("asus", NULL, NULL,
 							  &asus_backlight_data,
diff --git a/drivers/platform/x86/classmate-laptop.c b/drivers/platform/x86/classmate-laptop.c
index 341cbfe..0ade3a4 100644
--- a/drivers/platform/x86/classmate-laptop.c
+++ b/drivers/platform/x86/classmate-laptop.c
@@ -562,6 +562,7 @@ static int cmpc_ipml_add(struct acpi_device *acpi)
 		return -ENOMEM;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_PLATFORM;
 	props.max_brightness = 7;
 	ipml->bd = backlight_device_register("cmpc_bl", &acpi->dev,
 					     acpi->handle, &cmpc_bl_ops,
diff --git a/drivers/platform/x86/compal-laptop.c b/drivers/platform/x86/compal-laptop.c
index 097083c..1e66477 100644
--- a/drivers/platform/x86/compal-laptop.c
+++ b/drivers/platform/x86/compal-laptop.c
@@ -962,6 +962,7 @@ static int __init compal_init(void)
 	if (!acpi_video_backlight_support()) {
 		struct backlight_properties props;
 		memset(&props, 0, sizeof(struct backlight_properties));
+		props.type = BACKLIGHT_PLATFORM;
 		props.max_brightness = BACKLIGHT_LEVEL_MAX;
 		compalbl_device = backlight_device_register(DRIVER_NAME,
 							    NULL, NULL,
diff --git a/drivers/platform/x86/dell-laptop.c b/drivers/platform/x86/dell-laptop.c
index cf8a89a..3a54613 100644
--- a/drivers/platform/x86/dell-laptop.c
+++ b/drivers/platform/x86/dell-laptop.c
@@ -651,6 +651,7 @@ static int __init dell_init(void)
 	if (max_intensity) {
 		struct backlight_properties props;
 		memset(&props, 0, sizeof(struct backlight_properties));
+		props.type = BACKLIGHT_PLATFORM;
 		props.max_brightness = max_intensity;
 		dell_backlight_device = backlight_device_register("dell_backlight",
 								  &platform_device->dev,
diff --git a/drivers/platform/x86/eeepc-laptop.c b/drivers/platform/x86/eeepc-laptop.c
index b2edfdc..697505b 100644
--- a/drivers/platform/x86/eeepc-laptop.c
+++ b/drivers/platform/x86/eeepc-laptop.c
@@ -1136,6 +1136,7 @@ static int eeepc_backlight_init(struct eeepc_laptop *eeepc)
 	struct backlight_device *bd;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_PLATFORM;
 	props.max_brightness = 15;
 	bd = backlight_device_register(EEEPC_LAPTOP_FILE,
 				       &eeepc->platform_device->dev, eeepc,
diff --git a/drivers/platform/x86/eeepc-wmi.c b/drivers/platform/x86/eeepc-wmi.c
index 462ceab..29f607b 100644
--- a/drivers/platform/x86/eeepc-wmi.c
+++ b/drivers/platform/x86/eeepc-wmi.c
@@ -233,6 +233,7 @@ static int eeepc_wmi_backlight_init(struct eeepc_wmi *eeepc)
 
 	memset(&props, 0, sizeof(struct backlight_properties));
 	props.max_brightness = 15;
+	props.type = BACKLIGHT_PLATFORM;
 	bd = backlight_device_register(EEEPC_WMI_FILE,
 				       &platform_device->dev, eeepc,
 				       &eeepc_wmi_bl_ops, &props);
diff --git a/drivers/platform/x86/fujitsu-laptop.c b/drivers/platform/x86/fujitsu-laptop.c
index f44cd26..f5376c6 100644
--- a/drivers/platform/x86/fujitsu-laptop.c
+++ b/drivers/platform/x86/fujitsu-laptop.c
@@ -1128,6 +1128,7 @@ static int __init fujitsu_init(void)
 
 		memset(&props, 0, sizeof(struct backlight_properties));
 		max_brightness = fujitsu->max_brightness;
+		props.type = BACKLIGHT_PLATFORM;
 		props.max_brightness = max_brightness - 1;
 		fujitsu->bl_device = backlight_device_register("fujitsu-laptop",
 							       NULL, NULL,
diff --git a/drivers/platform/x86/msi-laptop.c b/drivers/platform/x86/msi-laptop.c
index 7e9bb6d..142d385 100644
--- a/drivers/platform/x86/msi-laptop.c
+++ b/drivers/platform/x86/msi-laptop.c
@@ -804,6 +804,7 @@ static int __init msi_init(void)
 	} else {
 		struct backlight_properties props;
 		memset(&props, 0, sizeof(struct backlight_properties));
+		props.type = BACKLIGHT_PLATFORM;
 		props.max_brightness = MSI_LCD_LEVEL_MAX - 1;
 		msibl_device = backlight_device_register("msi-laptop-bl", NULL,
 							 NULL, &msibl_ops,
diff --git a/drivers/platform/x86/msi-wmi.c b/drivers/platform/x86/msi-wmi.c
index 42a5469..064d8d6 100644
--- a/drivers/platform/x86/msi-wmi.c
+++ b/drivers/platform/x86/msi-wmi.c
@@ -252,6 +252,7 @@ static int __init msi_wmi_init(void)
 	if (!acpi_video_backlight_support()) {
 		struct backlight_properties props;
 		memset(&props, 0, sizeof(struct backlight_properties));
+		props.type = BACKLIGHT_PLATFORM;
 		props.max_brightness = ARRAY_SIZE(backlight_map) - 1;
 		backlight = backlight_device_register(DRV_NAME, NULL, NULL,
 						      &msi_backlight_ops,
diff --git a/drivers/platform/x86/panasonic-laptop.c b/drivers/platform/x86/panasonic-laptop.c
index cc1e0ba..05be30e 100644
--- a/drivers/platform/x86/panasonic-laptop.c
+++ b/drivers/platform/x86/panasonic-laptop.c
@@ -602,6 +602,7 @@ static int acpi_pcc_hotkey_add(struct acpi_device *device)
 	}
 	/* initialize backlight */
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_PLATFORM;
 	props.max_brightness = pcc->sinf[SINF_AC_MAX_BRIGHT];
 	pcc->backlight = backlight_device_register("panasonic", NULL, pcc,
 						   &pcc_backlight_ops, &props);
diff --git a/drivers/platform/x86/sony-laptop.c b/drivers/platform/x86/sony-laptop.c
index f200677..138d8ab 100644
--- a/drivers/platform/x86/sony-laptop.c
+++ b/drivers/platform/x86/sony-laptop.c
@@ -1297,6 +1297,7 @@ static int sony_nc_add(struct acpi_device *device)
 						&handle))) {
 							struct backlight_properties props;
 		memset(&props, 0, sizeof(struct backlight_properties));
+		props.type = BACKLIGHT_PLATFORM;
 		props.max_brightness = SONY_MAX_BRIGHTNESS - 1;
 		sony_backlight_device = backlight_device_register("sony", NULL,
 								  NULL,
diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
index 2d61186..6dedc97 100644
--- a/drivers/platform/x86/thinkpad_acpi.c
+++ b/drivers/platform/x86/thinkpad_acpi.c
@@ -6310,6 +6310,7 @@ static int __init brightness_init(struct ibm_init_struct *iibm)
 		return 1;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_PLATFORM;
 	props.max_brightness = bright_maxlvl;
 	props.brightness = b & TP_EC_BACKLIGHT_LVLMSK;
 	ibm_backlight_device = backlight_device_register(TPACPI_BACKLIGHT_DEV_NAME,
diff --git a/drivers/platform/x86/toshiba_acpi.c b/drivers/platform/x86/toshiba_acpi.c
index 06f304f..a5533a1 100644
--- a/drivers/platform/x86/toshiba_acpi.c
+++ b/drivers/platform/x86/toshiba_acpi.c
@@ -1017,6 +1017,7 @@ static int __init toshiba_acpi_init(void)
 		create_toshiba_proc_entries();
 	}
 
+	props.type = BACKLIGHT_PLATFORM;
 	props.max_brightness = HCI_LCD_BRIGHTNESS_LEVELS - 1;
 	toshiba_backlight_device = backlight_device_register("toshiba",
 							     &toshiba_acpi.p_dev->dev,
diff --git a/drivers/staging/olpc_dcon/olpc_dcon.c b/drivers/staging/olpc_dcon/olpc_dcon.c
index 75aa7a36..a5915f4 100644
--- a/drivers/staging/olpc_dcon/olpc_dcon.c
+++ b/drivers/staging/olpc_dcon/olpc_dcon.c
@@ -718,6 +718,7 @@ static int dcon_probe(struct i2c_client *client, const struct i2c_device_id *id)
 	}
 	else {
 		dcon_bl_dev->props.max_brightness = 15;
+		dcon_bl_dev->props.type = BACKLIGHT_RAW;
 		dcon_bl_dev->props.power = FB_BLANK_UNBLANK;
 		dcon_bl_dev->props.brightness = dcon_get_backlight();
 
diff --git a/drivers/staging/samsung-laptop/samsung-laptop.c b/drivers/staging/samsung-laptop/samsung-laptop.c
index eb44b60..6c55f38 100644
--- a/drivers/staging/samsung-laptop/samsung-laptop.c
+++ b/drivers/staging/samsung-laptop/samsung-laptop.c
@@ -488,6 +488,7 @@ static int __init samsung_init(void)
 
 	/* create a backlight device to talk to this one */
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_PLATFORM;
 	props.max_brightness = MAX_BRIGHT;
 	backlight_device = backlight_device_register("samsung", &sdev->dev,
 						     NULL, &backlight_ops,
diff --git a/drivers/usb/misc/appledisplay.c b/drivers/usb/misc/appledisplay.c
index 1fa6ce3..68ab460 100644
--- a/drivers/usb/misc/appledisplay.c
+++ b/drivers/usb/misc/appledisplay.c
@@ -282,6 +282,7 @@ static int appledisplay_probe(struct usb_interface *iface,
 	snprintf(bl_name, sizeof(bl_name), "appledisplay%d",
 		atomic_inc_return(&count_displays) - 1);
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = 0xff;
 	pdata->bd = backlight_device_register(bl_name, NULL, pdata,
 					      &appledisplay_bl_data, &props);
diff --git a/drivers/video/atmel_lcdfb.c b/drivers/video/atmel_lcdfb.c
index 8dce251..7d40604 100644
--- a/drivers/video/atmel_lcdfb.c
+++ b/drivers/video/atmel_lcdfb.c
@@ -127,6 +127,7 @@ static void init_backlight(struct atmel_lcdfb_info *sinfo)
 		return;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = 0xff;
 	bl = backlight_device_register("backlight", &sinfo->pdev->dev, sinfo,
 				       &atmel_lcdc_bl_ops, &props);
diff --git a/drivers/video/aty/aty128fb.c b/drivers/video/aty/aty128fb.c
index 34a0851..ac3b7e3 100644
--- a/drivers/video/aty/aty128fb.c
+++ b/drivers/video/aty/aty128fb.c
@@ -1818,6 +1818,7 @@ static void aty128_bl_init(struct aty128fb_par *par)
 	snprintf(name, sizeof(name), "aty128bl%d", info->node);
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = FB_BACKLIGHT_LEVELS - 1;
 	bd = backlight_device_register(name, info->dev, par, &aty128_bl_data,
 				       &props);
diff --git a/drivers/video/aty/atyfb_base.c b/drivers/video/aty/atyfb_base.c
index 5bf9123..9f9deb5 100644
--- a/drivers/video/aty/atyfb_base.c
+++ b/drivers/video/aty/atyfb_base.c
@@ -2241,6 +2241,7 @@ static void aty_bl_init(struct atyfb_par *par)
 	snprintf(name, sizeof(name), "atybl%d", info->node);
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = FB_BACKLIGHT_LEVELS - 1;
 	bd = backlight_device_register(name, info->dev, par, &aty_bl_data,
 				       &props);
diff --git a/drivers/video/aty/radeon_backlight.c b/drivers/video/aty/radeon_backlight.c
index 256966e..732f665 100644
--- a/drivers/video/aty/radeon_backlight.c
+++ b/drivers/video/aty/radeon_backlight.c
@@ -158,6 +158,7 @@ void radeonfb_bl_init(struct radeonfb_info *rinfo)
 	snprintf(name, sizeof(name), "radeonbl%d", rinfo->info->node);
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = FB_BACKLIGHT_LEVELS - 1;
 	bd = backlight_device_register(name, rinfo->info->dev, pdata,
 				       &radeon_bl_data, &props);
diff --git a/drivers/video/backlight/88pm860x_bl.c b/drivers/video/backlight/88pm860x_bl.c
index 38ffc3f..d5e51e2 100644
--- a/drivers/video/backlight/88pm860x_bl.c
+++ b/drivers/video/backlight/88pm860x_bl.c
@@ -227,6 +227,7 @@ static int pm860x_backlight_probe(struct platform_device *pdev)
 	}
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = MAX_BRIGHTNESS;
 	bl = backlight_device_register(name, &pdev->dev, data,
 					&pm860x_backlight_ops, &props);
diff --git a/drivers/video/backlight/adp5520_bl.c b/drivers/video/backlight/adp5520_bl.c
index 9f436e0..af31197 100644
--- a/drivers/video/backlight/adp5520_bl.c
+++ b/drivers/video/backlight/adp5520_bl.c
@@ -303,6 +303,7 @@ static int __devinit adp5520_bl_probe(struct platform_device *pdev)
 	mutex_init(&data->lock);
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = ADP5020_MAX_BRIGHTNESS;
 	bl = backlight_device_register(pdev->name, data->master, data,
 				       &adp5520_bl_ops, &props);
diff --git a/drivers/video/backlight/adp8860_bl.c b/drivers/video/backlight/adp8860_bl.c
index 734c650..d2a96a4 100644
--- a/drivers/video/backlight/adp8860_bl.c
+++ b/drivers/video/backlight/adp8860_bl.c
@@ -709,6 +709,7 @@ static int __devinit adp8860_probe(struct i2c_client *client,
 	i2c_set_clientdata(client, data);
 
 	memset(&props, 0, sizeof(props));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = ADP8860_MAX_BRIGHTNESS;
 
 	mutex_init(&data->lock);
diff --git a/drivers/video/backlight/adx_bl.c b/drivers/video/backlight/adx_bl.c
index fe9af12..c861c41 100644
--- a/drivers/video/backlight/adx_bl.c
+++ b/drivers/video/backlight/adx_bl.c
@@ -104,6 +104,7 @@ static int __devinit adx_backlight_probe(struct platform_device *pdev)
 	}
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = 0xff;
 	bldev = backlight_device_register(dev_name(&pdev->dev), &pdev->dev,
 					  bl, &adx_backlight_ops, &props);
diff --git a/drivers/video/backlight/atmel-pwm-bl.c b/drivers/video/backlight/atmel-pwm-bl.c
index e6a66da..0443a4f 100644
--- a/drivers/video/backlight/atmel-pwm-bl.c
+++ b/drivers/video/backlight/atmel-pwm-bl.c
@@ -168,6 +168,7 @@ static int atmel_pwm_bl_probe(struct platform_device *pdev)
 	}
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = pdata->pwm_duty_max - pdata->pwm_duty_min;
 	bldev = backlight_device_register("atmel-pwm-bl", &pdev->dev, pwmbl,
 					  &atmel_pwm_bl_ops, &props);
diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
index e207810..074502c 100644
--- a/drivers/video/backlight/backlight.c
+++ b/drivers/video/backlight/backlight.c
@@ -19,6 +19,12 @@
 #include <asm/backlight.h>
 #endif
 
+static const char *backlight_types[] = {
+	[BACKLIGHT_RAW] = "raw",
+	[BACKLIGHT_PLATFORM] = "platform",
+	[BACKLIGHT_FIRMWARE] = "firmware",
+};
+
 #if defined(CONFIG_FB) || (defined(CONFIG_FB_MODULE) && \
 			   defined(CONFIG_BACKLIGHT_CLASS_DEVICE_MODULE))
 /* This callback gets called when something important happens inside a
@@ -169,6 +175,14 @@ static ssize_t backlight_store_brightness(struct device *dev,
 	return rc;
 }
 
+static ssize_t backlight_show_type(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct backlight_device *bd = to_backlight_device(dev);
+
+	return sprintf(buf, "%s\n", backlight_types[bd->props.type]);
+}
+
 static ssize_t backlight_show_max_brightness(struct device *dev,
 		struct device_attribute *attr, char *buf)
 {
@@ -234,6 +248,7 @@ static struct device_attribute bl_device_attributes[] = {
 	__ATTR(actual_brightness, 0444, backlight_show_actual_brightness,
 		     NULL),
 	__ATTR(max_brightness, 0444, backlight_show_max_brightness, NULL),
+	__ATTR(type, 0444, backlight_show_type, NULL),
 	__ATTR_NULL,
 };
 
diff --git a/drivers/video/backlight/corgi_lcd.c b/drivers/video/backlight/corgi_lcd.c
index 1e71c35..af60983 100644
--- a/drivers/video/backlight/corgi_lcd.c
+++ b/drivers/video/backlight/corgi_lcd.c
@@ -562,6 +562,7 @@ static int __devinit corgi_lcd_probe(struct spi_device *spi)
 	lcd->mode = (pdata) ? pdata->init_mode : CORGI_LCD_MODE_VGA;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = pdata->max_intensity;
 	lcd->bl_dev = backlight_device_register("corgi_bl", &spi->dev, lcd,
 						&corgi_bl_ops, &props);
diff --git a/drivers/video/backlight/cr_bllcd.c b/drivers/video/backlight/cr_bllcd.c
index a4f4546..d7d1673 100644
--- a/drivers/video/backlight/cr_bllcd.c
+++ b/drivers/video/backlight/cr_bllcd.c
@@ -193,6 +193,7 @@ static int cr_backlight_probe(struct platform_device *pdev)
 	}
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	bdp = backlight_device_register("cr-backlight", &pdev->dev, NULL,
 					&cr_backlight_ops, &props);
 	if (IS_ERR(bdp)) {
diff --git a/drivers/video/backlight/da903x_bl.c b/drivers/video/backlight/da903x_bl.c
index 87659ed..62043f1 100644
--- a/drivers/video/backlight/da903x_bl.c
+++ b/drivers/video/backlight/da903x_bl.c
@@ -136,6 +136,7 @@ static int da903x_backlight_probe(struct platform_device *pdev)
 		da903x_write(data->da903x_dev, DA9034_WLED_CONTROL2,
 				DA9034_WLED_ISET(pdata->output_current));
 
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = max_brightness;
 	bl = backlight_device_register(pdev->name, data->da903x_dev, data,
 				       &da903x_backlight_ops, &props);
diff --git a/drivers/video/backlight/ep93xx_bl.c b/drivers/video/backlight/ep93xx_bl.c
index b0cc491..9f1e389 100644
--- a/drivers/video/backlight/ep93xx_bl.c
+++ b/drivers/video/backlight/ep93xx_bl.c
@@ -87,6 +87,7 @@ static int __init ep93xxbl_probe(struct platform_device *dev)
 	ep93xxbl->mmio = EP93XX_RASTER_BRIGHTNESS;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = EP93XX_MAX_BRIGHT;
 	bl = backlight_device_register(dev->name, &dev->dev, ep93xxbl,
 				       &ep93xxbl_ops, &props);
diff --git a/drivers/video/backlight/generic_bl.c b/drivers/video/backlight/generic_bl.c
index 312ca61..8c6befd 100644
--- a/drivers/video/backlight/generic_bl.c
+++ b/drivers/video/backlight/generic_bl.c
@@ -91,6 +91,7 @@ static int genericbl_probe(struct platform_device *pdev)
 		name = machinfo->name;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = machinfo->max_intensity;
 	bd = backlight_device_register(name, &pdev->dev, NULL, &genericbl_ops,
 				       &props);
diff --git a/drivers/video/backlight/hp680_bl.c b/drivers/video/backlight/hp680_bl.c
index 267d23f..38aa002 100644
--- a/drivers/video/backlight/hp680_bl.c
+++ b/drivers/video/backlight/hp680_bl.c
@@ -109,6 +109,7 @@ static int __devinit hp680bl_probe(struct platform_device *pdev)
 	struct backlight_device *bd;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = HP680_MAX_INTENSITY;
 	bd = backlight_device_register("hp680-bl", &pdev->dev, NULL,
 				       &hp680bl_ops, &props);
diff --git a/drivers/video/backlight/jornada720_bl.c b/drivers/video/backlight/jornada720_bl.c
index 2f177b3..40e4fa8 100644
--- a/drivers/video/backlight/jornada720_bl.c
+++ b/drivers/video/backlight/jornada720_bl.c
@@ -106,6 +106,7 @@ static int jornada_bl_probe(struct platform_device *pdev)
 	struct backlight_device *bd;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = BL_MAX_BRIGHT;
 	bd = backlight_device_register(S1D_DEVICENAME, &pdev->dev, NULL,
 				       &jornada_bl_ops, &props);
diff --git a/drivers/video/backlight/kb3886_bl.c b/drivers/video/backlight/kb3886_bl.c
index f439a86..72dd555 100644
--- a/drivers/video/backlight/kb3886_bl.c
+++ b/drivers/video/backlight/kb3886_bl.c
@@ -149,6 +149,7 @@ static int kb3886bl_probe(struct platform_device *pdev)
 		machinfo->limit_mask = -1;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = machinfo->max_intensity;
 	kb3886_backlight_device = backlight_device_register("kb3886-bl",
 							    &pdev->dev, NULL,
diff --git a/drivers/video/backlight/locomolcd.c b/drivers/video/backlight/locomolcd.c
index d2f5901..bbca312 100644
--- a/drivers/video/backlight/locomolcd.c
+++ b/drivers/video/backlight/locomolcd.c
@@ -184,6 +184,7 @@ static int locomolcd_probe(struct locomo_dev *ldev)
 	local_irq_restore(flags);
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = 4;
 	locomolcd_bl_device = backlight_device_register("locomo-bl",
 							&ldev->dev, NULL,
diff --git a/drivers/video/backlight/max8925_bl.c b/drivers/video/backlight/max8925_bl.c
index b2b2c7b..8d25610 100644
--- a/drivers/video/backlight/max8925_bl.c
+++ b/drivers/video/backlight/max8925_bl.c
@@ -136,6 +136,7 @@ static int __devinit max8925_backlight_probe(struct platform_device *pdev)
 	data->current_brightness = 0;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = MAX_BRIGHTNESS;
 	bl = backlight_device_register(name, &pdev->dev, data,
 					&max8925_backlight_ops, &props);
diff --git a/drivers/video/backlight/mbp_nvidia_bl.c b/drivers/video/backlight/mbp_nvidia_bl.c
index 1485f73..74c3394 100644
--- a/drivers/video/backlight/mbp_nvidia_bl.c
+++ b/drivers/video/backlight/mbp_nvidia_bl.c
@@ -367,6 +367,7 @@ static int __init mbp_init(void)
 		return -ENXIO;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_PLATFORM;
 	props.max_brightness = 15;
 	mbp_backlight_device = backlight_device_register("mbp_backlight", NULL,
 							 NULL,
diff --git a/drivers/video/backlight/omap1_bl.c b/drivers/video/backlight/omap1_bl.c
index d3bc562..08d26a7 100644
--- a/drivers/video/backlight/omap1_bl.c
+++ b/drivers/video/backlight/omap1_bl.c
@@ -146,6 +146,7 @@ static int omapbl_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = OMAPBL_MAX_INTENSITY;
 	dev = backlight_device_register("omap-bl", &pdev->dev, bl, &omapbl_ops,
 					&props);
diff --git a/drivers/video/backlight/pcf50633-backlight.c b/drivers/video/backlight/pcf50633-backlight.c
index 3c424f7..ef5628d 100644
--- a/drivers/video/backlight/pcf50633-backlight.c
+++ b/drivers/video/backlight/pcf50633-backlight.c
@@ -112,6 +112,7 @@ static int __devinit pcf50633_bl_probe(struct platform_device *pdev)
 	if (!pcf_bl)
 		return -ENOMEM;
 
+	bl_props.type = BACKLIGHT_RAW;
 	bl_props.max_brightness = 0x3f;
 	bl_props.power = FB_BLANK_UNBLANK;
 
diff --git a/drivers/video/backlight/progear_bl.c b/drivers/video/backlight/progear_bl.c
index 809278c..6af183d 100644
--- a/drivers/video/backlight/progear_bl.c
+++ b/drivers/video/backlight/progear_bl.c
@@ -84,6 +84,7 @@ static int progearbl_probe(struct platform_device *pdev)
 	pci_write_config_byte(sb_dev, SB_MPS1, temp | 0x20);
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = HW_LEVEL_MAX - HW_LEVEL_MIN;
 	progear_backlight_device = backlight_device_register("progear-bl",
 							     &pdev->dev, NULL,
diff --git a/drivers/video/backlight/pwm_bl.c b/drivers/video/backlight/pwm_bl.c
index 21866ec..2c2a2c7 100644
--- a/drivers/video/backlight/pwm_bl.c
+++ b/drivers/video/backlight/pwm_bl.c
@@ -108,6 +108,7 @@ static int pwm_backlight_probe(struct platform_device *pdev)
 		dev_dbg(&pdev->dev, "got pwm for backlight\n");
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = data->max_brightness;
 	bl = backlight_device_register(dev_name(&pdev->dev), &pdev->dev, pb,
 				       &pwm_backlight_ops, &props);
diff --git a/drivers/video/backlight/s6e63m0.c b/drivers/video/backlight/s6e63m0.c
index 5927db0..322040f 100644
--- a/drivers/video/backlight/s6e63m0.c
+++ b/drivers/video/backlight/s6e63m0.c
@@ -778,6 +778,7 @@ static int __devinit s6e63m0_probe(struct spi_device *spi)
 
 	bd->props.max_brightness = MAX_BRIGHTNESS;
 	bd->props.brightness = MAX_BRIGHTNESS;
+	bd->props.type = BACKLIGHT_RAW;
 	lcd->bd = bd;
 
 	/*
diff --git a/drivers/video/backlight/tosa_bl.c b/drivers/video/backlight/tosa_bl.c
index 2a04b38..425a736 100644
--- a/drivers/video/backlight/tosa_bl.c
+++ b/drivers/video/backlight/tosa_bl.c
@@ -102,6 +102,7 @@ static int __devinit tosa_bl_probe(struct i2c_client *client,
 	data->i2c = client;
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = 512 - 1;
 	data->bl = backlight_device_register("tosa-bl", &client->dev, data,
 					     &bl_ops, &props);
diff --git a/drivers/video/backlight/wm831x_bl.c b/drivers/video/backlight/wm831x_bl.c
index 08fd87f..d4c6eb2 100644
--- a/drivers/video/backlight/wm831x_bl.c
+++ b/drivers/video/backlight/wm831x_bl.c
@@ -193,6 +193,7 @@ static int wm831x_backlight_probe(struct platform_device *pdev)
 	data->current_brightness = 0;
 	data->isink_reg = isink_reg;
 
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = max_isel;
 	bl = backlight_device_register("wm831x", &pdev->dev, data,
 				       &wm831x_backlight_ops, &props);
diff --git a/drivers/video/bf54x-lq043fb.c b/drivers/video/bf54x-lq043fb.c
index e7d0f52..2464b91 100644
--- a/drivers/video/bf54x-lq043fb.c
+++ b/drivers/video/bf54x-lq043fb.c
@@ -649,6 +649,7 @@ static int __devinit bfin_bf54x_probe(struct platform_device *pdev)
 	}
 #ifndef NO_BL_SUPPORT
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = 255;
 	bl_dev = backlight_device_register("bf54x-bl", NULL, NULL,
 					   &bfin_lq043fb_bl_ops, &props);
diff --git a/drivers/video/bfin-t350mcqb-fb.c b/drivers/video/bfin-t350mcqb-fb.c
index 3cf7767..d8de29f 100644
--- a/drivers/video/bfin-t350mcqb-fb.c
+++ b/drivers/video/bfin-t350mcqb-fb.c
@@ -545,6 +545,7 @@ static int __devinit bfin_t350mcqb_probe(struct platform_device *pdev)
 	}
 #ifndef NO_BL_SUPPORT
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = 255;
 	bl_dev = backlight_device_register("bf52x-bl", NULL, NULL,
 					   &bfin_lq043fb_bl_ops, &props);
diff --git a/drivers/video/imxfb.c b/drivers/video/imxfb.c
index 5c363d0..01d1793 100644
--- a/drivers/video/imxfb.c
+++ b/drivers/video/imxfb.c
@@ -502,6 +502,7 @@ static void imxfb_init_backlight(struct imxfb_info *fbi)
 
 	memset(&props, 0, sizeof(struct backlight_properties));
 	props.max_brightness = 0xff;
+	props.type = BACKLIGHT_RAW;
 	writel(fbi->pwmr, fbi->regs + LCDC_PWMR);
 
 	bl = backlight_device_register("imxfb-bl", &fbi->pdev->dev, fbi,
diff --git a/drivers/video/nvidia/nv_backlight.c b/drivers/video/nvidia/nv_backlight.c
index 2fb552a..74ba5da 100644
--- a/drivers/video/nvidia/nv_backlight.c
+++ b/drivers/video/nvidia/nv_backlight.c
@@ -111,6 +111,7 @@ void nvidia_bl_init(struct nvidia_par *par)
 	snprintf(name, sizeof(name), "nvidiabl%d", info->node);
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = FB_BACKLIGHT_LEVELS - 1;
 	bd = backlight_device_register(name, info->dev, par, &nvidia_bl_ops,
 				       &props);
diff --git a/drivers/video/omap2/displays/panel-acx565akm.c b/drivers/video/omap2/displays/panel-acx565akm.c
index e773106..7e04c92 100644
--- a/drivers/video/omap2/displays/panel-acx565akm.c
+++ b/drivers/video/omap2/displays/panel-acx565akm.c
@@ -534,6 +534,7 @@ static int acx_panel_probe(struct omap_dss_device *dssdev)
 
 	props.fb_blank = FB_BLANK_UNBLANK;
 	props.power = FB_BLANK_UNBLANK;
+	props.type = BACKLIGHT_RAW;
 
 	bldev = backlight_device_register("acx565akm", &md->spi->dev,
 			md, &acx565akm_bl_ops, &props);
diff --git a/drivers/video/omap2/displays/panel-sharp-ls037v7dw01.c b/drivers/video/omap2/displays/panel-sharp-ls037v7dw01.c
index 9a138f6..d2b35d2 100644
--- a/drivers/video/omap2/displays/panel-sharp-ls037v7dw01.c
+++ b/drivers/video/omap2/displays/panel-sharp-ls037v7dw01.c
@@ -99,6 +99,7 @@ static int sharp_ls_panel_probe(struct omap_dss_device *dssdev)
 
 	memset(&props, 0, sizeof(struct backlight_properties));
 	props.max_brightness = dssdev->max_backlight_level;
+	props.type = BACKLIGHT_RAW;
 
 	bl = backlight_device_register("sharp-ls", &dssdev->dev, dssdev,
 			&sharp_ls_bl_ops, &props);
diff --git a/drivers/video/omap2/displays/panel-taal.c b/drivers/video/omap2/displays/panel-taal.c
index e1c765d..d16a7cd 100644
--- a/drivers/video/omap2/displays/panel-taal.c
+++ b/drivers/video/omap2/displays/panel-taal.c
@@ -729,6 +729,8 @@ static int taal_probe(struct omap_dss_device *dssdev)
 		props.max_brightness = 255;
 	else
 		props.max_brightness = 127;
+
+	props.type = BACKLIGHT_RAW;
 	bldev = backlight_device_register("taal", &dssdev->dev, dssdev,
 					  &taal_bl_ops, &props);
 	if (IS_ERR(bldev)) {
diff --git a/drivers/video/riva/fbdev.c b/drivers/video/riva/fbdev.c
index 618f36b..9058ba5 100644
--- a/drivers/video/riva/fbdev.c
+++ b/drivers/video/riva/fbdev.c
@@ -355,6 +355,7 @@ static void riva_bl_init(struct riva_par *par)
 	snprintf(name, sizeof(name), "rivabl%d", info->node);
 
 	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_RAW;
 	props.max_brightness = FB_BACKLIGHT_LEVELS - 1;
 	bd = backlight_device_register(name, info->dev, par, &riva_bl_ops,
 				       &props);
diff --git a/include/linux/backlight.h b/include/linux/backlight.h
index 4a3d52e..5b45437 100644
--- a/include/linux/backlight.h
+++ b/include/linux/backlight.h
@@ -32,6 +32,12 @@ enum backlight_update_reason {
 	BACKLIGHT_UPDATE_SYSFS,
 };
 
+enum backlight_type {
+	BACKLIGHT_RAW,
+	BACKLIGHT_PLATFORM,
+	BACKLIGHT_FIRMWARE,
+};
+
 struct backlight_device;
 struct fb_info;
 
@@ -62,6 +68,8 @@ struct backlight_properties {
 	/* FB Blanking active? (values as for power) */
 	/* Due to be removed, please use (state & BL_CORE_FBBLANK) */
 	int fb_blank;
+	/* Backlight type */
+	enum backlight_type type;
 	/* Flags used to signal drivers of state changes */
 	/* Upper 4 bits are reserved for driver internal use */
 	unsigned int state;
-- 
1.7.3.2