[PATCH 7/7] drm/i915: add some assertions to hsw_disable_lcpll

[Paulo Zanoni <przanoni@gmail.com>]

From: Paulo Zanoni <paulo.r.zanoni@intel.com>

Most of the hardware needs to be disabled before LCPLL is disabled, so
let's add a function to assert some of items listed in the "Display
Sequences for LCPLL disabling" documentation.

The idea is that hsw_disable_lcpll should not disable the hardware,
the callers need to take care of calling hsw_disable_lcpll only once
everything is already disabled.

Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
---
 drivers/gpu/drm/i915/i915_reg.h      |  8 ++++++++
 drivers/gpu/drm/i915/intel_display.c | 28 ++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 8e5a5ec..9556dff 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -2195,6 +2195,8 @@
 #define BLC_PWM_CPU_CTL2	0x48250
 #define BLC_PWM_CPU_CTL		0x48254
 
+#define HSW_BLC_PWM2_CTL	0x48350
+
 /* PCH CTL1 is totally different, all but the below bits are reserved. CTL2 is
  * like the normal CTL from gen4 and earlier. Hooray for confusing naming. */
 #define BLC_PWM_PCH_CTL1	0xc8250
@@ -2203,6 +2205,12 @@
 #define   BLM_PCH_POLARITY			(1 << 29)
 #define BLC_PWM_PCH_CTL2	0xc8254
 
+#define UTIL_PIN_CTL		0x48400
+#define   UTIL_PIN_ENABLE	(1 << 31)
+
+#define PCH_GTC_CTL		0xe7000
+#define   PCH_GTC_ENABLE	(1 << 31)
+
 /* TV port control */
 #define TV_CTL			0x68000
 /** Enables the TV encoder */
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index ffb08bf..9055f60 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -5922,6 +5922,32 @@ static bool ironlake_get_pipe_config(struct intel_crtc *crtc,
 	return true;
 }
 
+static void assert_can_disable_lcpll(struct drm_i915_private *dev_priv)
+{
+	struct drm_device *dev = dev_priv->dev;
+	struct intel_ddi_plls *plls = &dev_priv->ddi_plls;
+	struct intel_crtc *crtc;
+
+	list_for_each_entry(crtc, &dev->mode_config.crtc_list, base.head)
+		WARN(crtc->base.enabled, "CRTC for pipe %c enabled\n",
+		     pipe_name(crtc->pipe));
+
+	WARN(I915_READ(HSW_PWR_WELL_DRIVER), "Power well on\n");
+	WARN(plls->spll_refcount, "SPLL enabled\n");
+	WARN(plls->wrpll1_refcount, "WRPLL1 enabled\n");
+	WARN(plls->wrpll2_refcount, "WRPLL2 enabled\n");
+	WARN(I915_READ(PCH_PP_STATUS) & PP_ON, "Panel power on\n");
+	WARN(I915_READ(BLC_PWM_CPU_CTL2) & BLM_PWM_ENABLE,
+	     "CPU PWM1 enabled\n");
+	WARN(I915_READ(HSW_BLC_PWM2_CTL) & BLM_PWM_ENABLE,
+	     "CPU PWM2 enabled\n");
+	WARN(I915_READ(BLC_PWM_PCH_CTL1) & BLM_PCH_PWM_ENABLE,
+	     "PCH PWM1 enabled\n");
+	WARN(I915_READ(UTIL_PIN_CTL) & UTIL_PIN_ENABLE,
+	     "Utility pin enabled\n");
+	WARN(I915_READ(PCH_GTC_CTL) & PCH_GTC_ENABLE, "PCH GTC enabled\n");
+}
+
 /*
  * This function implements pieces of two sequences from BSpec:
  * - Sequence for display software to disable LCPLL
@@ -5935,6 +5961,8 @@ void hsw_disable_lcpll(struct drm_i915_private *dev_priv,
 {
 	uint32_t val;
 
+	assert_can_disable_lcpll(dev_priv);
+
 	val = I915_READ(LCPLL_CTL);
 
 	if (switch_to_fclk) {
-- 
1.8.1.2