[WIP][PATCH 11/11] drm/i915: Turn off clocks when disp2d is powered down

ville.syrjala
2014-06-13T10:39:46Z

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

Set some bits in CCK/CCU to turn off display clocks when disp2d is power
gated. Not sure this really helps with anything. Docs aren't all that clear.

XXX: Doesn't actually work. CCK_DISPLAY_REF_CLOCK_CONTROL and CCU_ICLK_5
writes don't have any effect on the registers for some reason. When clock
gating disp2d via Punit CCK_DISPLAY_REF_CLOCK_CONTROL trunk off force bit
gets set but again direct write has no effect.
---
drivers/gpu/drm/i915/i915_reg.h | 5 +++++
drivers/gpu/drm/i915/intel_pm.c | 35 +++++++++++++++++++++++++++++++++++
2 files changed, 40 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 2aa9a3c..be88b13 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -584,12 +584,17 @@ enum punit_power_well {
#define DSI_PLL_M1_DIV_SHIFT 0
#define DSI_PLL_M1_DIV_MASK (0x1ff << 0)
#define CCK_DISPLAY_CLOCK_CONTROL 0x6b
+#define CCK_DISPLAY_REF_CLOCK_CONTROL 0x6c
#define DISPLAY_TRUNK_FORCE_ON (1 << 17)
#define DISPLAY_TRUNK_FORCE_OFF (1 << 16)
#define DISPLAY_FREQUENCY_STATUS (0x1f << 8)
#define DISPLAY_FREQUENCY_STATUS_SHIFT 8
#define DISPLAY_FREQUENCY_VALUES (0x1f << 0)

+#define CCU_ICLK_5 0x114
+#define DISPSS_CLKREQ (1 << 1)
+#define DISPBEND_CLKREQ (1 << 0)
+
/**
* DOC: DPIO
*
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index d8e20d3..96614c3 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -6057,6 +6057,20 @@ static void vlv_display_power_well_enable(struct drm_i915_private *dev_priv,
{
WARN_ON_ONCE(power_well->data != PUNIT_POWER_WELL_DISP2D);

+ mutex_lock(&dev_priv->dpio_lock);
+ /*
+ * (re)enable ref clocks at CCU
+ * FIXME maybe move to cmnlane?
+ */
+ vlv_ccu_write(dev_priv, CCU_ICLK_5,
+ vlv_ccu_read(dev_priv, CCU_ICLK_5) |
+ DISPBEND_CLKREQ | DISPSS_CLKREQ);
+ /*
+ * Punit clears CCK trunk force off bits
+ * automagically while ungating disp2d
+ */
+ mutex_unlock(&dev_priv->dpio_lock);
+
vlv_set_power_well(dev_priv, power_well, true);

spin_lock_irq(&dev_priv->irq_lock);
@@ -6085,6 +6099,27 @@ static void vlv_display_power_well_disable(struct drm_i915_private *dev_priv,
spin_unlock_irq(&dev_priv->irq_lock);

vlv_set_power_well(dev_priv, power_well, false);
+
+ mutex_lock(&dev_priv->dpio_lock);
+ /*
+ * Punit doesn't set the CCK trunk force off bits when power gating
+ * disp2d. It does set them when clock gating disp2d, but we ask it
+ * to power gate instead of clock gate.
+ */
+ vlv_cck_write(dev_priv, CCK_DISPLAY_CLOCK_CONTROL,
+ vlv_cck_read(dev_priv, CCK_DISPLAY_CLOCK_CONTROL) |
+ DISPLAY_TRUNK_FORCE_OFF);
+ vlv_cck_write(dev_priv, CCK_DISPLAY_REF_CLOCK_CONTROL,
+ vlv_cck_read(dev_priv, CCK_DISPLAY_REF_CLOCK_CONTROL) |
+ DISPLAY_TRUNK_FORCE_OFF);
+ /*
+ * disable ref clocks at CCU
+ * FIXME maybe move to cmnlane?
+ */
+ vlv_ccu_write(dev_priv, CCU_ICLK_5,
+ vlv_ccu_read(dev_priv, CCU_ICLK_5) &
+ ~(DISPBEND_CLKREQ | DISPSS_CLKREQ));
+ mutex_unlock(&dev_priv->dpio_lock);
}

static void vlv_dpio_cmn_power_well_enable(struct drm_i915_private *dev_priv,
--
1.8.5.5