drm/gma500: Refactor backlight support (v2)

Refactor backlight support so that the gma_backlight_enable() /
gma_backlight_disable() / gma_backlight_set() functions used by
the Opregion handle will also work if no backlight_device gets
registered.

This is a preparation patch for not registering the gma500's own backlight
device when acpi_video should be used, since registering 2 backlight
devices for a single display really is undesirable.

Since the acpi-video interface often uses the OpRegion we need to keep
the OpRegion functional even when dev_priv->backlight_device is NULL.

As a result of this refactor the actual backlight_device_register()
call is moved to the shared backlight.c code and all #ifdefs related to
CONFIG_BACKLIGHT_CLASS_DEVICE are now also limited to backlight.c .

No functional changes intended.

This has been tested on a Packard Bell Dot SC (Intel Atom N2600, cedarview)
and a Sony Vaio vpc-x11s1e (Intel N540, poulsbo) laptop.

Changes in v2:
- Fix unused variable warnings when CONFIG_BACKLIGHT is not selected by
  marking the 2 variables as  __maybe_unused.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220917205920.647212-2-hdegoede@redhat.com

1 files changed, 9 insertions, 41 deletions

diff --git a/drivers/gpu/drm/gma500/cdv_device.c b/drivers/gpu/drm/gma500/cdv_device.c
index ce96234f3df2..3065596257e9 100644
--- a/drivers/gpu/drm/gma500/cdv_device.c
+++ b/drivers/gpu/drm/gma500/cdv_device.c
@@ -5,7 +5,6 @@
  *
  **************************************************************************/
 
-#include <linux/backlight.h>
 #include <linux/delay.h>
 
 #include <drm/drm.h>
@@ -62,14 +61,10 @@ static int cdv_output_init(struct drm_device *dev)
 	return 0;
 }
 
-#ifdef CONFIG_BACKLIGHT_CLASS_DEVICE
-
 /*
  *	Cedartrail Backlght Interfaces
  */
 
-static struct backlight_device *cdv_backlight_device;
-
 static int cdv_backlight_combination_mode(struct drm_device *dev)
 {
 	return REG_READ(BLC_PWM_CTL2) & PWM_LEGACY_MODE;
@@ -92,9 +87,8 @@ static u32 cdv_get_max_backlight(struct drm_device *dev)
 	return max;
 }
 
-static int cdv_get_brightness(struct backlight_device *bd)
+static int cdv_get_brightness(struct drm_device *dev)
 {
-	struct drm_device *dev = bl_get_data(bd);
 	struct pci_dev *pdev = to_pci_dev(dev->dev);
 	u32 val = REG_READ(BLC_PWM_CTL) & BACKLIGHT_DUTY_CYCLE_MASK;
 
@@ -106,20 +100,13 @@ static int cdv_get_brightness(struct backlight_device *bd)
 		val *= lbpc;
 	}
 	return (val * 100)/cdv_get_max_backlight(dev);
-
 }
 
-static int cdv_set_brightness(struct backlight_device *bd)
+static void cdv_set_brightness(struct drm_device *dev, int level)
 {
-	struct drm_device *dev = bl_get_data(bd);
 	struct pci_dev *pdev = to_pci_dev(dev->dev);
-	int level = bd->props.brightness;
 	u32 blc_pwm_ctl;
 
-	/* Percentage 1-100% being valid */
-	if (level < 1)
-		level = 1;
-
 	level *= cdv_get_max_backlight(dev);
 	level /= 100;
 
@@ -136,38 +123,18 @@ static int cdv_set_brightness(struct backlight_device *bd)
 	blc_pwm_ctl = REG_READ(BLC_PWM_CTL) & ~BACKLIGHT_DUTY_CYCLE_MASK;
 	REG_WRITE(BLC_PWM_CTL, (blc_pwm_ctl |
 				(level << BACKLIGHT_DUTY_CYCLE_SHIFT)));
-	return 0;
 }
 
-static const struct backlight_ops cdv_ops = {
-	.get_brightness = cdv_get_brightness,
-	.update_status  = cdv_set_brightness,
-};
-
 static int cdv_backlight_init(struct drm_device *dev)
 {
 	struct drm_psb_private *dev_priv = to_drm_psb_private(dev);
-	struct backlight_properties props;
-
-	memset(&props, 0, sizeof(struct backlight_properties));
-	props.max_brightness = 100;
-	props.type = BACKLIGHT_PLATFORM;
-
-	cdv_backlight_device = backlight_device_register("psb-bl",
-					NULL, (void *)dev, &cdv_ops, &props);
-	if (IS_ERR(cdv_backlight_device))
-		return PTR_ERR(cdv_backlight_device);
-
-	cdv_backlight_device->props.brightness =
-			cdv_get_brightness(cdv_backlight_device);
-	backlight_update_status(cdv_backlight_device);
-	dev_priv->backlight_device = cdv_backlight_device;
-	dev_priv->backlight_enabled = true;
+
+	dev_priv->backlight_level = cdv_get_brightness(dev);
+	cdv_set_brightness(dev, dev_priv->backlight_level);
+
 	return 0;
 }
 
-#endif
-
 /*
  *	Provide the Cedarview specific chip logic and low level methods
  *	for power management
@@ -613,9 +580,10 @@ const struct psb_ops cdv_chip_ops = {
 	.hotplug = cdv_hotplug_event,
 	.hotplug_enable = cdv_hotplug_enable,
 
-#ifdef CONFIG_BACKLIGHT_CLASS_DEVICE
 	.backlight_init = cdv_backlight_init,
-#endif
+	.backlight_get = cdv_get_brightness,
+	.backlight_set = cdv_set_brightness,
+	.backlight_name = "psb-bl",
 
 	.init_pm = cdv_init_pm,
 	.save_regs = cdv_save_display_registers,