Before extending this to SKL let's document DVFS a bit.
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
---
drivers/gpu/drm/i915/intel_cdclk.c | 55 ++++++++++++++++++++++++++++++-----
drivers/gpu/drm/i915/intel_dpll_mgr.c | 16 +++++-----
drivers/gpu/drm/i915/intel_drv.h | 8 ++---
3 files changed, 60 insertions(+), 19 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_cdclk.c b/drivers/gpu/drm/i915/intel_cdclk.c
index 8111a13079e1..58ee4dd07cf6 100644
--- a/drivers/gpu/drm/i915/intel_cdclk.c
+++ b/drivers/gpu/drm/i915/intel_cdclk.c
@@ -1510,7 +1510,22 @@ static void cnl_cdclk_pll_enable(struct drm_i915_private *dev_priv, int vco)
dev_priv->cdclk.hw.vco = vco;
}
-int cnl_dvfs_pre_change(struct drm_i915_private *dev_priv)
+/**
+ * DOC: Display Voltage and Frequency Switching (DVFS)
+ *
+ * DVFS is used to adjust the display voltage to match the display clock
+ * frequencies. To save power the voltage is set to minimum when disabling PLL.
+ *
+ */
+
+/**
+ * intel_dvfs_pre_change - (DVFS) Sequence Before Frequency Change
+ * @dev_priv: i915 device
+ *
+ * The sequence before frequency change is the following and it requests
+ * the power controller to raise voltage to maximum
+ */
+int intel_dvfs_pre_change(struct drm_i915_private *dev_priv)
{
int ret;
@@ -1528,14 +1543,31 @@ int cnl_dvfs_pre_change(struct drm_i915_private *dev_priv)
return ret;
}
-void cnl_dvfs_post_change(struct drm_i915_private *dev_priv, int level)
+/**
+ * intel_dvfs_post_change - (DVFS) Sequence After Frequency Change
+ * @dev_priv: i915 device
+ * @level: New desired voltage-frequency level.
+ *
+ * The sequence after frequency change is the following and it requests
+ * the port controller to lower voltage to the minimum.
+ */
+void intel_dvfs_post_change(struct drm_i915_private *dev_priv, int level)
{
mutex_lock(&dev_priv->rps.hw_lock);
sandybridge_pcode_write(dev_priv, SKL_PCODE_CDCLK_CONTROL, level);
mutex_unlock(&dev_priv->rps.hw_lock);
}
-int cnl_dvfs_new_level(int cdclk, int portclk)
+/**
+ * intel_dvfs_new_level - DVFS get new level.
+ * @cdclk: CD Clock.
+ * @portclk: Link rate. Optional argument. When 0, only cdclk is enough.
+ *
+ * Returns:
+ * New required level that should be informed to pcode
+ * based on @cdclk and on @portclk, if available.
+ */
+int intel_dvfs_new_level(int cdclk, int portclk)
{
if (cdclk == 168000 && portclk <= 594000)
return 0;
@@ -1545,7 +1577,16 @@ int cnl_dvfs_new_level(int cdclk, int portclk)
return 2;
}
-bool cnl_dvfs_needs_change(struct drm_i915_private *dev_priv, int level)
+/**
+ * intel_dvfs_needs_change - DVFS needs change.
+ * @dev_priv: i915 device
+ * @level: New desired voltage-frequency level.
+ *
+ * Returns:
+ * True if current level known by pcode is different of the
+ * new desired one.
+ */
+bool intel_dvfs_needs_change(struct drm_i915_private *dev_priv, int level)
{
int old_level;
@@ -1562,7 +1603,7 @@ static void cnl_set_cdclk(struct drm_i915_private *dev_priv,
int vco = cdclk_state->vco;
u32 val, divider, level;
- if (cnl_dvfs_pre_change(dev_priv))
+ if (intel_dvfs_pre_change(dev_priv))
return;
/* cdclk = vco / 2 / div{1,2} */
@@ -1597,8 +1638,8 @@ static void cnl_set_cdclk(struct drm_i915_private *dev_priv,
I915_WRITE(CDCLK_CTL, val);
/* inform PCU of the change */
- level = cnl_dvfs_new_level(cdclk, 0);
- cnl_dvfs_post_change(dev_priv, level);
+ level = intel_dvfs_new_level(cdclk, 0);
+ intel_dvfs_post_change(dev_priv, level);
intel_update_cdclk(dev_priv);
}
diff --git a/drivers/gpu/drm/i915/intel_dpll_mgr.c b/drivers/gpu/drm/i915/intel_dpll_mgr.c
index 4eb1be91a669..55997389a29f 100644
--- a/drivers/gpu/drm/i915/intel_dpll_mgr.c
+++ b/drivers/gpu/drm/i915/intel_dpll_mgr.c
@@ -2014,10 +2014,10 @@ static void cnl_ddi_pll_enable(struct drm_i915_private *dev_priv,
*/
cdclk = dev_priv->cdclk.hw.cdclk;
portclk = intel_ddi_port_clock(dev_priv, pll->id);
- level = cnl_dvfs_new_level(cdclk, portclk);
- change_level = cnl_dvfs_needs_change(dev_priv, level);
+ level = intel_dvfs_new_level(cdclk, portclk);
+ change_level = intel_dvfs_needs_change(dev_priv, level);
if (change_level)
- ret = cnl_dvfs_pre_change(dev_priv);
+ ret = intel_dvfs_pre_change(dev_priv);
/* 6. Enable DPLL in DPLL_ENABLE. */
val = I915_READ(CNL_DPLL_ENABLE(pll->id));
@@ -2038,7 +2038,7 @@ static void cnl_ddi_pll_enable(struct drm_i915_private *dev_priv,
* (DVFS) Sequence After Frequency Change
*/
if (change_level && ret == 0)
- cnl_dvfs_post_change(dev_priv, level);
+ intel_dvfs_post_change(dev_priv, level);
/*
* 9. turn on the clock for the DDI and map the DPLL to the DDI
@@ -2065,10 +2065,10 @@ static void cnl_ddi_pll_disable(struct drm_i915_private *dev_priv,
* (DVFS) Sequence Before Frequency Change
*/
cdclk = dev_priv->cdclk.hw.cdclk;
- level = cnl_dvfs_new_level(cdclk, 0);
- change_level = cnl_dvfs_needs_change(dev_priv, level);
+ level = intel_dvfs_new_level(cdclk, 0);
+ change_level = intel_dvfs_needs_change(dev_priv, level);
if (change_level)
- ret = cnl_dvfs_pre_change(dev_priv);
+ ret = intel_dvfs_pre_change(dev_priv);
/* 3. Disable DPLL through DPLL_ENABLE. */
val = I915_READ(CNL_DPLL_ENABLE(pll->id));
@@ -2089,7 +2089,7 @@ static void cnl_ddi_pll_disable(struct drm_i915_private *dev_priv,
* (DVFS) Sequence After Frequency Change
*/
if (change_level && ret == 0)
- cnl_dvfs_post_change(dev_priv, level);
+ intel_dvfs_post_change(dev_priv, level);
/* 6. Disable DPLL power in DPLL_ENABLE. */
val = I915_READ(CNL_DPLL_ENABLE(pll->id));
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 8621110401e3..567b6e846a69 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -1323,10 +1323,10 @@ void skl_init_cdclk(struct drm_i915_private *dev_priv);
void skl_uninit_cdclk(struct drm_i915_private *dev_priv);
void cnl_init_cdclk(struct drm_i915_private *dev_priv);
void cnl_uninit_cdclk(struct drm_i915_private *dev_priv);
-int cnl_dvfs_pre_change(struct drm_i915_private *dev_priv);
-void cnl_dvfs_post_change(struct drm_i915_private *dev_priv, int level);
-int cnl_dvfs_new_level(int cdclk, int portclk);
-bool cnl_dvfs_needs_change(struct drm_i915_private *dev_priv, int level);
+int intel_dvfs_pre_change(struct drm_i915_private *dev_priv);
+void intel_dvfs_post_change(struct drm_i915_private *dev_priv, int level);
+int intel_dvfs_new_level(int cdclk, int portclk);
+bool intel_dvfs_needs_change(struct drm_i915_private *dev_priv, int level);
void bxt_init_cdclk(struct drm_i915_private *dev_priv);
void bxt_uninit_cdclk(struct drm_i915_private *dev_priv);
void intel_init_cdclk_hooks(struct drm_i915_private *dev_priv);
--
2.13.5
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