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, 4 insertions, 69 deletions

diff --git a/drivers/gpu/drm/gma500/psb_device.c b/drivers/gpu/drm/gma500/psb_device.c
index 71534f4ca834..3c294c38bdb4 100644
--- a/drivers/gpu/drm/gma500/psb_device.c
+++ b/drivers/gpu/drm/gma500/psb_device.c
@@ -5,8 +5,6 @@
  *
  **************************************************************************/
 
-#include <linux/backlight.h>
-
 #include <drm/drm.h>
 
 #include "gma_device.h"
@@ -24,8 +22,6 @@ static int psb_output_init(struct drm_device *dev)
 	return 0;
 }
 
-#ifdef CONFIG_BACKLIGHT_CLASS_DEVICE
-
 /*
  *	Poulsbo Backlight Interfaces
  */
@@ -41,18 +37,6 @@ static int psb_output_init(struct drm_device *dev)
 #define PSB_BACKLIGHT_PWM_POLARITY_BIT_CLEAR (0xFFFE)
 #define PSB_BACKLIGHT_PWM_CTL_SHIFT	(16)
 
-static int psb_brightness;
-static struct backlight_device *psb_backlight_device;
-
-static int psb_get_brightness(struct backlight_device *bd)
-{
-	/* return locally cached var instead of HW read (due to DPST etc.) */
-	/* FIXME: ideally return actual value in case firmware fiddled with
-	   it */
-	return psb_brightness;
-}
-
-
 static int psb_backlight_setup(struct drm_device *dev)
 {
 	struct drm_psb_private *dev_priv = to_drm_psb_private(dev);
@@ -86,62 +70,13 @@ static int psb_backlight_setup(struct drm_device *dev)
 		REG_WRITE(BLC_PWM_CTL,
 			(value << PSB_BACKLIGHT_PWM_CTL_SHIFT) | (value));
 	}
-	return 0;
-}
-
-static int psb_set_brightness(struct backlight_device *bd)
-{
-	struct drm_device *dev = bl_get_data(psb_backlight_device);
-	int level = bd->props.brightness;
-
-	/* Percentage 1-100% being valid */
-	if (level < 1)
-		level = 1;
-
-	psb_intel_lvds_set_brightness(dev, level);
-	psb_brightness = level;
-	return 0;
-}
-
-static const struct backlight_ops psb_ops = {
-	.get_brightness = psb_get_brightness,
-	.update_status  = psb_set_brightness,
-};
-
-static int psb_backlight_init(struct drm_device *dev)
-{
-	struct drm_psb_private *dev_priv = to_drm_psb_private(dev);
-	int ret;
-	struct backlight_properties props;
-
-	memset(&props, 0, sizeof(struct backlight_properties));
-	props.max_brightness = 100;
-	props.type = BACKLIGHT_PLATFORM;
-
-	psb_backlight_device = backlight_device_register("psb-bl",
-					NULL, (void *)dev, &psb_ops, &props);
-	if (IS_ERR(psb_backlight_device))
-		return PTR_ERR(psb_backlight_device);
-
-	ret = psb_backlight_setup(dev);
-	if (ret < 0) {
-		backlight_device_unregister(psb_backlight_device);
-		psb_backlight_device = NULL;
-		return ret;
-	}
-	psb_backlight_device->props.brightness = 100;
-	psb_backlight_device->props.max_brightness = 100;
-	backlight_update_status(psb_backlight_device);
-	dev_priv->backlight_device = psb_backlight_device;
 
+	psb_intel_lvds_set_brightness(dev, PSB_MAX_BRIGHTNESS);
 	/* This must occur after the backlight is properly initialised */
 	psb_lid_timer_init(dev_priv);
-
 	return 0;
 }
 
-#endif
-
 /*
  *	Provide the Poulsbo specific chip logic and low level methods
  *	for power management
@@ -345,9 +280,9 @@ const struct psb_ops psb_chip_ops = {
 
 	.output_init = psb_output_init,
 
-#ifdef CONFIG_BACKLIGHT_CLASS_DEVICE
-	.backlight_init = psb_backlight_init,
-#endif
+	.backlight_init = psb_backlight_setup,
+	.backlight_set = psb_intel_lvds_set_brightness,
+	.backlight_name = "psb-bl",
 
 	.init_pm = psb_init_pm,
 	.save_regs = psb_save_display_registers,