[PATCH 3/4] drm/i915: add quirk to indicate that an alt bit is used for brightness inversion

Carsten Emde
2012-04-26T17:00:13Z

[-- Attachment #1: drivers-gpu-drm-i915-add-quirk-to-check-alt-bit-for-backlight-brightness-inversion.patch --]
[-- Type: text/plain, Size: 3010 bytes --]

Bit #28 of the backlight control BLC_PWM_CTL2 is normally used
to indicate whether the brightness of the panel backlight is
inverted. Sometimes, however, bit #29 is used for this purpose.
Add a quirk to mark machines that do so.

Signed-off-by: Carsten Emde <C.Emde@osadl.org>

---
drivers/gpu/drm/i915/i915_drv.h | 1 +
drivers/gpu/drm/i915/i915_reg.h | 1 +
drivers/gpu/drm/i915/intel_display.c | 10 ++++++++++
drivers/gpu/drm/i915/intel_panel.c | 12 ++++++++++--
4 files changed, 22 insertions(+), 2 deletions(-)

Index: linux-tip/drivers/gpu/drm/i915/i915_drv.h
===================================================================
--- linux-tip.orig/drivers/gpu/drm/i915/i915_drv.h
+++ linux-tip/drivers/gpu/drm/i915/i915_drv.h
@@ -295,6 +295,7 @@ enum intel_pch {

#define QUIRK_PIPEA_FORCE (1<<0)
#define QUIRK_LVDS_SSC_DISABLE (1<<1)
+#define QUIRK_ALT_BIT_FOR_BRIGHTNESS_INVERSION (2<<1)

struct intel_fbdev;
struct intel_fbc_work;
Index: linux-tip/drivers/gpu/drm/i915/i915_reg.h
===================================================================
--- linux-tip.orig/drivers/gpu/drm/i915/i915_reg.h
+++ linux-tip/drivers/gpu/drm/i915/i915_reg.h
@@ -1685,6 +1685,7 @@
/* Backlight control */
#define BLC_PWM_CTL2 0x61250 /* 965+ only */
#define BLM_COMBINATION_MODE (1 << 30)
+#define BLM_ALT_POLARITY_I965 (1 << 29) /* quirk only */
#define BLM_POLARITY_I965 (1 << 28) /* gen4 only */
#define BLC_PWM_CTL 0x61254
/*
Index: linux-tip/drivers/gpu/drm/i915/intel_display.c
===================================================================
--- linux-tip.orig/drivers/gpu/drm/i915/intel_display.c
+++ linux-tip/drivers/gpu/drm/i915/intel_display.c
@@ -9101,6 +9101,16 @@ static void quirk_ssc_force_disable(stru
dev_priv->quirks |= QUIRK_LVDS_SSC_DISABLE;
}

+/*
+ * A machine may use an alternate bit to indicate panel backlight brightness
+ * inversion
+ */
+static void quirk_alt_bit_for_brightness_inversion(struct drm_device *dev)
+{
+ struct drm_i915_private *dev_priv = dev->dev_private;
+ dev_priv->quirks |= QUIRK_ALT_BIT_FOR_BRIGHTNESS_INVERSION;
+}
+
struct intel_quirk {
int device;
int subsystem_vendor;
Index: linux-tip/drivers/gpu/drm/i915/intel_panel.c
===================================================================
--- linux-tip.orig/drivers/gpu/drm/i915/intel_panel.c
+++ linux-tip/drivers/gpu/drm/i915/intel_panel.c
@@ -208,9 +208,17 @@ static u32 intel_panel_compute_brightnes
dev_priv->quirks & QUIRK_INVERT_BRIGHTNESS)
return intel_panel_get_max_backlight(dev) - val;

- /* gen4 has a polarity bit */
- if (IS_GEN4(dev) && (I915_READ(BLC_PWM_CTL2) & BLM_POLARITY_I965))
+ if (IS_GEN4(dev)) {
+ /* gen4 has a - possibly quirked - polarity bit */
+ int mask;
+
+ if (dev_priv->quirks & QUIRK_ALT_BIT_FOR_BRIGHTNESS_INVERSION)
+ mask = BLM_ALT_POLARITY_I965;
+ else
+ mask = BLM_POLARITY_I965;
+ if (I915_READ(BLC_PWM_CTL2) & mask)
return intel_panel_get_max_backlight(dev) - val;
+ }

return val;
}